2021 GMC Sierra 1500

The volume 2021 Sierra 1500 configuration — an Elevation/SLT crew cab 4WD on the 5.3L L84 EcoTec3 V8 — makes 355 hp, unchanged within the fourth generation that began in 2019. 2021 fields five engines, the widest menu this nameplate ever offered, topping out with the 420-hp 6.2L V8 in AT4 and Denali.

The volume 5.3L V8 peaks at 383 lb-ft, squarely mid-pack for a half-ton and well below the 800 lb-ft top of the truck band. The 2021 torque leaders are the 6.2L V8 and the 3.0L Duramax, tied at 460 lb-ft; note the 2.7L Turbo is still the pre-TurboMax 348 lb-ft engine, a year before the 430-lb-ft revision.

No instrumented test of a 2021 Sierra on the volume 5.3L/8-speed drivetrain was located, so the figure comes from the mechanically identical Silverado 1500 in the same configuration, which Edmunds timed at 7.0 seconds. Adequate for a half-ton, but a truck band anchored by sub-3-second electric pickups leaves it in the bottom third.

The 5.3L and 6.2L small-blocks deliver the lag-free low-end torque that defines a half-ton — reviewers describe the 5.3L's acceleration as brisk with a throaty exhaust note that quiets to near-silence at cruise — and the 3.0L Duramax is unusually smooth and hushed for a diesel. Two things hold it out of the top band: the pre-TurboMax 2.7L four is strong off idle but coarse when worked, and Active/Dynamic Fuel Management cylinder deactivation is audible and occasionally rough at light throttle, a complaint sharpened in 2021 because the semiconductor shortage forced GM to build many mid-year 5.3L trucks with it deleted entirely.

2021 is the most transmission-fragmented year of this generation: the 5.3L V8 alone ships behind a six-speed, an eight-speed and a ten-speed depending on trim, and for 2021 GMC specifically removed the 5.3L/10-speed combination from SLE and Elevation, leaving those volume trims on the weakest of the three. The 10-speed on SLT, AT4, Denali, the 6.2L and the Duramax is smooth and keeps the engine in its band; the carry-over 6L80 six-speed on base Sierra is plainly dated against a segment that had moved to eight and ten ratios.

Properly equipped, the 2021 Sierra 1500 tows 11,800 lbs — strong for a half-ton but short of the 13,300 lbs its Silverado twin advertises, because GMC does not offer the 6.2L in the light 2WD double-cab configuration that produces Chevrolet's headline number. Raised trailering ratings for the 2.7L Turbo and the Duramax were among the year's advertised improvements.

Maximum payload for 2021 is 2,250 lbs in a base 4.3L V6 2WD configuration — mid-pack for a half-ton and a long way from the 3,400-lb top of the truck band. The volume 5.3L crew cab lands near 2,150 lbs, and the heavier diesel gives up roughly 400 lbs of it.

GMC's ProGrade Trailering System was the most complete factory towing suite in the segment for 2021, and the camera side of it was expressly upgraded that year: up to 15 views including a transparent-trailer rendering, plus new Trailer Length Indicator, Jack-Knife Alert, Cargo Bed View Enhancement, Rear Trailer View with guidelines and a Trailer-Angle Indicator, over the top of an available integrated trailer brake controller, tow/haul mode with sway control, trailer profiles and a pre-departure checklist. It stops just short of the top band because the brake controller, the trailer camera provisions and the accessory camera itself are all extra-cost, and because the MultiPro tailgate fouls some hitch setups.

Four-wheel drive is offered on every 2021 Sierra 1500 trim from base Sierra to Denali and is standard on AT4, using a genuine two-speed Autotrac transfer case with a low range and a dash selector for 2WD / Auto 4WD / 4WD; an automatic locking rear differential is widely available. It falls short of the top only because 4WD remains an extra-cost option on the mainstream trims rather than standard equipment.

The AT4 is a genuinely capable light-duty off-roader — 2-inch factory suspension lift, Rancho monotube dampers, skid plates, automatic locking rear differential, hill descent control, two-speed transfer case and, new for 2021, Goodyear Wrangler Territory all-terrains and an off-road high-clearance step — and 2021 widened the reach by adding the X31 Off-Road and Protection Package to SLE, Elevation and SLT. It cannot reach the top band because this model year has no halo off-roader: the Multimatic-damped AT4X, with its front and rear lockers and 33-inch tires, is still two model years away, so nothing here answers a Raptor or a TRD Pro.

Five genuinely distinct engines — a 4.3L V6, a 2.7L turbo four, two small-block V8s and an inline-six turbo-diesel — give the 2021 Sierra 1500 the broadest conventional powertrain menu in the half-ton class and the widest this nameplate would ever offer, since the 4.3L V6, the AFM 5.3L and the six-speed are all deleted within two model years. It cannot reach the top band because none of them is electrified: there is no hybrid, plug-in or battery-electric Sierra 1500 for 2021, and the Sierra EV is a separate nameplate on another platform.

The volume 5.3L V8 4WD returns 18 MPG combined — thirsty even by full-size truck standards and the main drag on this category, landing in the bottom quarter of a truck band that runs to 27 MPG. A 2021 buyer chasing economy had to move to the 2.7L Turbo or, far more dramatically, to the 3.0L Duramax, whose 26 MPG combined in 2WD is the most efficient half-ton powertrain of the year.

16 MPG in town is mid-pack for a V8 half-ton, and Dynamic Fuel Management cylinder deactivation is exactly what keeps it off the bottom — the 2021 chip-shortage builds that shipped without DFM drop to 14 MPG city, a two-MPG penalty inside one model year. Stop-and-start use is where this truck costs the most to run.

21 MPG on the highway is ordinary for a 4WD V8 half-ton and sits in the lower third of a truck band topping out at 31 MPG. The 3.0L Duramax is the only 2021 Sierra powertrain that changes the picture, and in 2WD form its 30 MPG highway rating nearly clears the band outright.

A 24-gallon tank and 18 MPG combined give the volume crew cab roughly 430 miles between fills — usable but short of the 500-plus miles a diesel half-ton delivers, and well down a truck band that runs to 700 miles. The figure is derived from the EPA combined rating and the published tank capacity rather than quoted directly by EPA, which publishes no range estimate for gasoline vehicles.

EPA puts annual fuel spend for the volume 5.3L V8 4WD configuration at $3,450 — high in absolute terms and in the upper half of the truck band. The 6.2L V8's premium-fuel requirement is the real penalty in this lineup, pushing AT4 and Denali buyers past $4,500 a year, while the cheapest Sierra to feed is the 2.7L Turbo in 2WD at $2,950.

The volume 5.3L V8, the 4.3L V6 and the 2.7L Turbo all make their rated output on regular 87-octane unleaded, and one 5.3L six-speed build is additionally E85 flex-fuel capable, which adds a cheap-fuel option where E85 is sold. The score is held below the top band because the 6.2L V8 requires premium — a genuine running-cost penalty precisely on the AT4 and Denali trims GMC sells most eagerly — and the Duramax brings diesel plus DEF.

NHTSA gives the 2021 Sierra 1500 four stars overall. The side results are maxed out — 5 stars in both the side barrier and the side pole test — but the frontal result is 4 stars (4 driver, 4 passenger on the volume Crew Cab), and that is what holds the composite one star short. Rollover is 4 stars, better than the 3 stars a tall 4WD full-size pickup often posts.

The 2021 Sierra 1500 Crew Cab earns Good in driver-side small overlap, moderate overlap front, the original side test, roof strength (4.62 strength-to-weight) and head restraints — but drops to Marginal in the passenger-side small overlap front test, where the structure itself is rated Poor, and only Acceptable in the updated side test with Marginal rear-passenger torso protection. A Marginal result in a key crashworthiness test on the side a family passenger sits, plus Poor headlights on every variant, puts any Top Safety Pick award out of reach.

This is the 2021 Sierra's worst safety failing: no collision-avoidance hardware is standard on the volume trim. A Sierra SLE leaves the lot with six airbags, a rear vision camera and Teen Driver — automatic emergency braking, forward collision alert, lane keep assist with lane departure warning and IntelliBeam are all inside the $1,045 Driver Alert Package II, and adaptive cruise is a further option. 2021 widened where these could be ordered rather than making any of them standard; the refreshed 2022 Sierra is the year the GMC Pro Safety content became standard across the lineup. For contrast, the 2021 Ford F-150 shipped Co-Pilot360 with AEB, blind-spot monitoring and lane keeping standard on every trim.

When the truck is actually fitted with it, the system performs at the top of the IIHS scale: Superior in vehicle-to-vehicle front crash prevention, avoiding the collision outright at both 12 and 25 mph. What keeps it out of the top band is that IIHS published no vehicle-to-pedestrian rating for the 2021 Sierra, so front pedestrian braking is unverified and nighttime pedestrian performance is entirely unmeasured — exactly the scenario in which a tall-hooded full-size pickup is most dangerous to people outside it.

Lane Change Alert with Side Blind Zone Alert and Rear Cross Traffic Alert are alert-only — no steering or braking intervention — and are option-package content on the volume SLE and Elevation trims, becoming standard equipment only as you climb to Denali. There is no trailer-length blind-spot coverage on the 2021 Sierra 1500, which is a real gap on a truck bought to tow; that capability arrives with the later refresh.

Lane Keep Assist with Lane Departure Warning is optional package content and is a reactive nudge by design — GM's own documentation for this generation states it is not intended to keep the vehicle centered in the lane, and it only operates above roughly 37 mph, so it does nothing on secondary roads. No lane centering of any kind is offered on the 2021 Sierra 1500 at any trim or price.

Full-speed-range adaptive cruise is competent when equipped — reviewers describe the 2021 Sierra's adaptive cruise and lane-keeping aids as operating smoothly with few false alerts — and 2021 expanded where it could be ordered, to every trim above the base Sierra. But it stays option-package content stacked on top of the Driver Alert Package, so the great majority of 2021 Sierras left the factory with plain cruise control, and there is no highway-assist layer combining ACC with steering support this model year.

Super Cruise is not offered on the 2021 Sierra 1500 at any trim or price. GM did not extend hands-free driving to the Sierra until late in the 2022 model year, and then only on Crew Cab Denali (standard on Denali Ultimate) — by which point Ford had been selling BlueCruise on the F-150 since 2021.

IIHS rated all four 2021 Sierra 1500 headlight variations Poor — the worst possible result, uniform across the range, so there is no trim a buyer can move up to in order to escape it. None of the four are curve-adaptive and visibility was judged inadequate on curves in every test. IntelliBeam automatic high beams are available, but only inside the optional Driver Alert Package, and auto-dimming does not fix a low-beam pattern this weak.

The commanding seating position does not translate into good sightlines: the tall, broad hood hides the road immediately ahead and thick forward pillars cut into the view to either side, with over-the-shoulder visibility on the Crew Cab a recurring reviewer complaint. GMC's camera compensation is the best of the GM twins — HD Surround Vision and the ProGrade Trailering camera views, plus the Rear Camera Mirror, genuinely cover the blind zones — but every one of those is upper-trim or package content, so the volume SLE relies on a single rear camera and its mirrors.

IIHS rates the 2021 Sierra 1500's LATCH ease of use Marginal — the second-worst grade — with anchors buried too deep in the seat bight, hard to find, and other hardware in the seat easily mistaken for them. The Crew Cab's own dimensions work in the buyer's favour once a seat is in: near-square door openings, a flat floor and stretch-out rear legroom make the installation less cramped than in most rivals, which is the only reason this lands mid-40s rather than lower.

The volume 2021 Sierra 1500 Crew Cab seats five with front buckets, and six when ordered with the 40/20/40 split bench that is standard equipment on base Sierra, SLE and Elevation. Cab and seat architecture is unchanged from the fourth generation's 2019 launch and identical to the 2023–2026 Sierra scorecards in this catalog.

43.0 in of front headroom sits at the very top of the 38–43 in truck band and is unchanged across the whole fourth generation — the same figure this catalog carries on the 2023 through 2026 Sierra and on the mechanically identical Silverado 1500.

44.5 in of front legroom is generous even by full-size truck standards and lands near the top of the 41–45 in truck band. Front-row space is not a compromise in any 2021 Sierra cab style.

Second-row headroom in the volume Crew Cab is comfortable for adults but a step behind the tallest-roofed half-tons, landing about two-thirds up the 38–41 in truck band. Unchanged since the generation launched for 2019.

43.4 in of second-row legroom makes the Crew Cab a genuine four-adult vehicle, level with the F-150 SuperCrew and well up the 33–45 in truck band. The Double Cab gives up more than eight inches of it, which is why the Crew Cab is the configuration nearly every retail buyer orders.

The volume Crew Cab pairs with the 5'8" Short Box, which sits low in the 54–98 in truck band — the unavoidable price of the long cab. Buyers who need bed length can order the 6'6" box on the Crew Cab, and only the shorter cabs reach the 8'2" box.

GM's wide, tall bed extracts more volume from the short box than any half-ton rival's comparable bed — 62.9 cu ft from a box barely longer than the F-150's 5.5-ft bed — which is why the bed volume score sits well above the bed length score.

2021 is the year the six-function MultiPro tailgate — the cleverest load-access device in the segment, with an inner gate, a load stop, a step and a fold-out work surface — became standard equipment on SLE and Elevation rather than upper-trim content, leaving only the base Sierra without it as a $595 option. Add LED bed lighting standard from SLE, 12 fixed tie-downs, lockable under-rear-seat storage and the CarbonPro carbon-fiber bed on AT4 and Denali, and this is a clear step above its Silverado twin. It falls short of the top band because the pre-refresh cabin's console and door bins are ordinary and there is no RamBox-style in-bed trunk.

Reviewers consistently call the front seats comfortable and supportive, and the Sierra gets there on cheaper trims than the Silverado does — a power-adjustable driver's seat, heated front seats and a heated leather-wrapped wheel are all standard from SLE, where the equivalent Chevrolet still had four-way manual adjustment. What keeps it mid-band is firm cushioning front and rear and a Crew Cab bench reviewers say needs more padding for long stints.

The leaf-sprung rear axle is tuned for load robustness, and unladen ride is this truck's acknowledged weak point — smooth on good highway and even on gravel, but firm and jostled by large bumps, with the redesigned F-150 and coil-sprung Ram 1500 clearly ahead by 2021. It grades a step above the Silverado because GMC's segment-exclusive continuous-damping Adaptive Ride Control is standard on Denali, a real fix but one no SLE or Elevation buyer can order.

A quiet cabin is one of the few refinement areas where this truck is consistently praised rather than excused — the 5.3L V8 falls to near-silence at a steady cruise and reviewers describe the Crew Cab as well isolated at highway speed. It stays short of the top band because 2021 predates the acoustic glass and active noise cancellation that the 2022 overhaul spread through the range, so wind rush around the large mirrors and coarse-surface tire roar are still audible.

This is where GMC's premium positioning actually pays the buyer back. Dual-zone automatic climate control, heated front seats and a heated leather-wrapped steering wheel are all standard from SLE — one rung above base — where the comparably priced Silverado LT still buries them in Convenience Packages. Ventilated front seats and heated rear outboard seats come at SLT and above. It stops short of the top band because ventilation and rear-seat heating remain upper-trim content and the base Sierra makes do with single-zone manual air.

The 2021 Sierra 1500's entry point was $30,100 before GM's $1,695 destination freight charge, roughly $1,600 above the equivalent Chevrolet Silverado 1500 WT on identical hardware — the standing GMC premium. The base trim used the 4.3L V6 and was the only 2021 Sierra without the MultiPro tailgate.

SLT Crew Cab 4WD is the Sierra's representative mid-ladder configuration, opening at $50,800 plus $1,695 destination with the 5.3L V8, MultiPro tailgate, ProGrade Trailering, leather-appointed seating and dual-zone climate standard; a typically-equipped truck with the SLT Premium package and 20-inch wheels lands near $53,900. The Sierra's real-world mix runs richer still — Denali is roughly a third of Sierra volume, and GMC's Q4 2021 Sierra average transaction price was $63,181.

Two independent estimators bracket the Sierra between roughly $3,200 and $3,650 over five years — cheap for a full-size truck, helped by commodity GM parts, a very large dealer network and simple pushrod V8 hardware. RepairPal flags above-average repair severity when something does break, but a low frequency of unscheduled repairs.

Among the stronger residuals in a segment that already holds value well, and a shade ahead of the mechanically identical Silverado — the GMC badge and the Denali-heavy used supply both transact higher. Kelley Blue Book named the 2021 Sierra a Top 10 Best Resale Value vehicle.

GM's standard bumper-to-bumper term, identical on every 2021 Sierra 1500 trim including Denali, and identical to Ford, Ram and Toyota — the segment floor. GMC charges a premium over Chevrolet on price but not a minute of extra coverage.

GM's standard powertrain term and the segment floor, matched by Ford and Ram and beaten by Toyota's Tundra only on the extended-service side. The optional 3.0L Duramax diesel's emissions components carry federally mandated 8-year/80,000-mile coverage, which does not extend the base powertrain term on the gas truck scored here.

GMC Pro Grade Protection on a 2021 Sierra covered exactly one scheduled maintenance visit — oil and filter change, tire rotation, multi-point inspection — having been cut from two visits after the 2018 model year, plus 5-year/60,000-mile roadside assistance, courtesy transportation during warranty repairs, 6-year/100,000-mile rust-through coverage, and a 3-month OnStar/Connected Services trial atop the 5-year OnStar Basic plan. That is a token maintenance package against Toyota's 2-year/25,000-mile ToyotaCare on the Tundra, and identical to what Chevrolet bundled with the Silverado despite the Sierra's higher price.

$53,900 volume-trim price minus its estimated resale value after 5 years (60% retained, or about $32,340) leaves about $21,560 in depreciation. Add the projected $3,400 in 5-year maintenance and repairs, and owning this vehicle for 5 years costs about $24,960 in total.

2021 is the worst-graded year of this fourth-generation truck and the sources disagree about how bad. Consumer Reports gave the 2021 Sierra 1500 a predicted-reliability score of 13 out of 100 and named it — alongside its mechanically identical Silverado 1500 twin — as the only full-size pickups on its '10 Least Reliable Vehicles' list, with persistent trouble in brakes and in-car electronics plus lesser transmission and power-accessory problems. The owner-complaint record backs the pessimism: engine problems alone run to 196 logged complaints for this model year. The counterweight is J.D. Power, whose consumer quality-and-reliability rating for the 2021 Sierra 1500 sits at 84/100, inside its 'great' band. Scored in the below-average band but off its floor, because the JDP result and the truck's average RepairPal repair frequency argue the CR figure is the harsh end of a genuine spread rather than the whole picture.

GMC's dependability standing is the clearest place the Sierra grades below its Chevrolet twin, and two studies bracketing this model year both put the brand below average. The J.D. Power 2021 Vehicle Dependability Study placed GMC at 143 PP100 against a 121 PP100 industry average — near the bottom of the survey, and well behind Chevrolet at 115 and GM stablemates Buick and Cadillac at 100 each. The 2024 VDS, which measures three-year-old 2021 model-year vehicles and so speaks directly to this truck, put GMC at 206 PP100 and 18th of 29 brands, again below the 190 PP100 average. Consumer Reports has placed GMC in the lower-middle group of mainstream brands across the same period. Below mid-pack rather than bottom-third: the brand still clears Ram and Jeep and has never anchored a study.

Seven NHTSA campaigns touch the 2021 Sierra 1500, and two of them are safety-restraint defects on the volume configuration: unsecured front-row center seat-belt brackets (20V792000, 624,216 units) and incorrect seat-belt bolts (20V811000). Two more are supplier tire campaigns (overcured Continentals, 20V684000; a 17-inch spare incompatible with accessory wheels that can disable ABS, 21V985000). Three of the seven miss the scored gas 5.3L truck entirely — the 6.2L connecting-rod/crankshaft program (25V274000, 597,571 units) and the diesel transmission control-valve recall with its 2026 re-do (24V797000, 26V083000) — which is what keeps this above the bottom band. What holds it down is the bulletin record beneath the recalls: GM issued a valve-lifter service update covering 2019–2021 V8s, and shift-quality bulletins for the 8- and 10-speed automatics run through the generation, so an elevated campaign count sits on top of an already busy TSB history.

The scored volume configuration is the 355-hp 5.3L L84 EcoTec3 V8 with the 8-speed automatic, and 2019–2021 is the window in which GM's Dynamic Fuel Management valve-lifter failures were at their worst — collapsed lifters, bent pushrods and lifter separation, documented on 2021 Sierras at average failure mileages around 4,300 and in one logged case a DFM lifter assembly failing at 15,873 miles. GM named 2019-and-later L84 trucks explicitly in its valve-lifter service update, and engine complaints are the largest single category in this model year's owner record. Two things stop the score falling further: the Gen V small-block architecture underneath is proven and universally serviceable, and from March 2021 the semiconductor shortage had GM shipping 5.3L trucks under RPO YK9 with cylinder deactivation deleted outright, so those specific builds sidestep the DFM failure mode entirely at a cost of roughly 1 MPG combined. The 8-speed carries its own shudder and shift-quality bulletins; only the 3.0L Duramax inline-six, outside the scored gas class, has a clean record here.

2021 is the last full model year of the pre-refresh fourth-generation cabin, and GMC's premium positioning makes its shortcomings count double on an item graded relative to price. Reviewers found hard plastic panels with large seams, cheap black plastic around the stereo and a stitched leather dashboard that feels hard and artificial — substantially the same materials as the cheaper Silverado. Even the range-topping Denali drew the criticism directly: The Drive called it an aging luxury car in a new pickup wrapper, and reviewers noted that GMC's claim to be the only premium half-ton reads as disingenuous against the Ram 1500 Limited and F-150 Limited. It rates a few points above the Silverado only because the Sierra's upper trims genuinely add open-pore wood and real aluminum, and because the volume SLE/Elevation trim carries somewhat better soft-touch coverage than an equivalent Chevrolet. This is exactly the deficiency the 2022 overhaul was built to fix, which is why the 2023 truck sits a full band higher.

Structural assembly of the third-year fourth-generation body at Fort Wayne, Silao and Oshawa is segment-normal — panel gaps and sheetmetal alignment are not what owners complain about. The problems are electronic and functional: Consumer Reports identified brakes and in-car electronics as this truck's persistent trouble spots, with less serious transmission and power-equipment issues behind them, and the owner record is dominated by engine and electrical faults rather than build defects. 2021 is also a compromised build year in its own right, with the semiconductor shortage forcing mid-year content deletions and shipping changes across GM's truck plants. Below the segment midpoint, and below the more settled post-refresh trucks.

The Buick-GMC channel runs roughly 1,600–1,650 US franchises — about half Chevrolet's footprint, and the one structural disadvantage the Sierra carries against its mechanically identical twin — but it is still near-nationwide coverage backed by GM's shared parts and service infrastructure, and dense in the rural markets where full-size trucks sell hardest. Service satisfaction is a genuine strength rather than a weakness: J.D. Power's Customer Service Index has repeatedly placed GMC at or near the top of the truck segment, and Buick-GMC dealers have led GM in dealership-satisfaction surveys. What costs the item a couple of points against later model years is capacity under load: 2021 owners waiting on valve-lifter repairs reported multi-week holds at dealerships while parts were backordered, which is the network being tested by this specific model year's defect rate.

Everything mechanical under the Sierra is shared with the Silverado 1500 — the second-best-selling vehicle in America — plus the Tahoe, Suburban, Yukon and Escalade, so the 5.3L small-block is the most familiar powertrain in any independent shop in the country and OEM, reman and aftermarket supply is deep. RepairPal puts the Sierra 1500's average annual repair and maintenance at $727 against a $936 full-size-truck average, ranking it 3rd of 17 in the class, with unscheduled shop visits at 0.2 per year versus 0.3 for the segment — cheap and infrequent, though individual repairs skew more severe than average, which is a fair description of the DFM lifter exposure. At five years old the truck now has a mature used- and reman-parts channel a current-year truck lacks. Two things keep it out of the top band: GMC-specific body panels, grilles and Denali-tier trim cost more than the Chevrolet equivalents, and the 2021-specific caveat is supply rather than price, with chip-shortage-era modules and lifter parts genuinely backordered during the warranty period.

2021 is the last full model year before the 2022 refresh brought a 13.4-inch display, so eight inches is not merely the volume figure but the maximum any Sierra 1500 could be ordered with — the floor of the 8–18.5 in truck band in a catalog anchored on 2026.

The GMC Infotainment System is one of the better-liked platforms of its era — quick to respond, logically laid out, with sharp graphics and real knobs plus hard climate buttons rather than menu-diving. What holds it below the top band in 2026 terms is the small 8-inch canvas, dated graphics and a control layout reviewers find an awkward reach from the driver's seat.

2021 is the model year wireless phone projection arrived on the Sierra — GMC lists it under 'New for 2021' — and it reaches the buyer earlier here than on the Chevrolet twin, standard from SLT up rather than only at the top two trims. Wired CarPlay and Android Auto are standard across the whole range including the base 7-inch system, and wireless is available lower down on SLE and Elevation, but it is not standard on those volume trims, which is what keeps this out of the top band.

Voice recognition is the pre-natural-language GM system — command-driven, workable for radio and phone, and comfortably outclassed by the Siri or Google assistant a projected phone brings in. Built-in navigation is not standard on the volume SLE or Elevation: the Premium GMC Infotainment System with navigation is SLT package content and standard only at the top, so most owners navigate through CarPlay.

A seven-speaker Bose system is available from SLE up and standard on Denali, and the Sierra adds something no rival offers — the MultiPro Audio System by Kicker, a Bluetooth speaker integrated into the tailgate. SiriusXM became standard on SLE and Elevation for 2021, which lifts the everyday listening experience on the volume trims. It stays mid-band because Bose here is a mid-tier branded system rather than a showpiece and the base six-speaker setup is ordinary.

No 2021 Sierra 1500 offers a full-digital cluster at any price. Instruments are an analog speedometer and tachometer flanking a Driver Information Center — 4.2-inch colour on most trims, an 8-inch colour DIC at the top of the range. The 12.3-inch configurable cluster is a 2022 arrival on this nameplate.

The 2021 Sierra 1500 predates the VIP (Global B) electrical architecture that the 2022.5 refresh brought to this nameplate, so over-the-air work is limited to infotainment and map/software refreshes pushed through the connected system rather than whole-vehicle module programming. Real capability, but narrow, and nothing that adds vehicle features after purchase.

The myGMC app covers the core set well — remote start and climate, lock/unlock, vehicle locate, diagnostics and fuel level, at a longer effective range than the fob — and remote start is standard equipment as far down as SLE for 2021. It is held to mid-band because the useful remote functions depend on an OnStar Remote Access plan once the included trial expires, and there is no phone-as-key on this generation.

The Crew Cab carries USB ports in both rows — SLE specifically adds two more over the base trim — in a mix of USB-A and USB-C rather than the all-C, high-wattage layouts newer trucks use, and a 120V household outlet is standard from SLT with a bed outlet available. Wireless phone charging is not available on the volume SLE or Elevation for 2021; it is SLT package content and standard only on Denali.

Keyless Open with push-button start and remote start are standard from SLE — one rung above base, and a rung lower than the comparable Silverado, where Keyless Open is LT-and-above content. Elevation adds a remote-locking tailgate and the MultiPro tailgate itself is fob-operated. It stops short of the top band because there is no phone-as-key on this generation, the base Sierra still uses a conventional key, and the 2020 model year had already deleted the rear-door keyless access buttons.

This is the truck's strongest technology suit and the year GMC widened its lead. A rear camera is standard, HD Surround Vision gives a bird's-eye view, and the ProGrade Trailering camera suite reaches up to 15 views — more than any rival pickup — with 2021 adding a Trailer Length Indicator, Jack-Knife Alert, Cargo Bed View Enhancement, Rear Trailer View guidelines and a Trailer-Angle Indicator. What keeps it out of the top band is that surround view, the rear camera mirror and several trailer views are package or accessory content rather than standard, and there is no automated parking.

GMC's 15-inch diagonal multicolour head-up display — a first-in-class item showing speed, tachometer, audio, phone, navigation and safety alerts — is offered on SLT, AT4 and Denali through the Technology Package, so it reaches one rung further down the ladder than the Silverado's High-Country-only equivalent. It is still optional everywhere and absent from the SLE and Elevation trims most buyers order, which keeps it mid-band.

The Crew Cab's 43.4 in of rear legroom and near-square, wide-opening rear doors make seat installation and buckling genuinely easy, and the rear bench cushions flip up for a flat floor big enough for strollers and bags. It is pulled down by a high step-in small children cannot manage without the optional power-assist steps, LATCH anchors IIHS rates Marginal for ease of use, and a cargo bed open to the weather unless a tonneau is fitted.

This is the 2021 Sierra's clearest failing for a family buyer, and it is worse than the truck's overall safety picture suggests. No collision-avoidance hardware is standard on the volume SLE or Elevation — automatic emergency braking, forward collision alert, lane keep assist and IntelliBeam all sit inside a $1,045 Driver Alert Package — and a family that does pay for it still gets a 4-star NHTSA overall result, a Marginal IIHS passenger-side small overlap rating with a structure rated Poor, and headlights IIHS rated Poor in all four variations with no trim offering an escape.

Space is not the problem — four adults plus gear travel easily in a cabin reviewers repeatedly call quiet, with rear vents in the Crew Cab and a bed that swallows whatever the cabin cannot. The limits are comfort and amenity rather than capacity: a firm unladen ride that gets jostled by large bumps, rear cushions that want more padding, heated rear outboard seats reserved for SLT and above, and no rear entertainment or rear fast-charging of note.

The 5.3L V8 pulls smoothly from low revs with brisk, lag-free response, the automatic shifts unobtrusively, and the commanding forward view makes the truck undemanding in traffic once you accept the size. Working against it: adaptive cruise control is stacked option-package content rather than standard on any volume trim, the auto stop/start restart is a recurring owner complaint for this year, and the sheer 232-inch footprint makes stop-and-go a chore.

The volume 5.3L V8 4WD Crew Cab returns 18 MPG combined and an EPA-estimated $3,450 a year in fuel — among the most expensive per-mile propositions any commuter could choose short of a heavy-duty, and worse still on the mid-2021 chip-shortage builds that shipped without Dynamic Fuel Management at 16 MPG and $3,900. Consumables are cheap and regular 87-octane is fine, and the 3.0L Duramax is genuinely thrifty at 24–26 MPG combined, but that is not what the volume buyer drives.

A 232-inch-long, 81.2-inch-wide Crew Cab needing 46.4 ft to turn around is a genuine liability in a garage or a city lot, and it overhangs a standard parking bay. The camera suite is the mitigation and it is the best in the segment — a rear camera is standard and HD Surround Vision gives a bird's-eye view — but surround view is package content the volume SLE or Elevation often leaves the lot without, and there is no automated parking.

This is what the truck is built for. The volume 5.3L V8 tows 11,000–11,300 lbs, the range tops out at 11,800 lbs with the 6.2L and the Max Trailering Package, payload reaches 2,250 lbs, and 2021 specifically raised the 2.7L Turbo and 3.0L Duramax ratings. The bed is the widest and highest-volume in the half-ton class and the small-block does not run out of breath under load. It grades just below its Silverado twin only because GMC does not offer the 6.2L in the light 2WD Double Cab that produces Chevrolet's 13,300-lb headline number.

A fully boxed frame, the small-block V8 and GM's 8- and 10-speed automatics are as fleet-proven as anything in the segment, and everything mechanical is shared with the Silverado 1500 so any shop in the country knows it. The reservation is specific and it is real for a hard-worked truck: 2019–2021 is the window in which the 5.3L's Dynamic Fuel Management valve-lifter failures were at their worst, and Consumer Reports named the 2021 Sierra and Silverado the only full-size pickups on its 10 Least Reliable Vehicles list.

2021 is an unusually strong year for this specifically, and it is where the Sierra separates from its twin. The six-function MultiPro tailgate — inner gate, load stop, step, work surface — became standard equipment on SLE and Elevation rather than upper-trim content, LED bed lighting is standard from SLE, ProGrade Trailering with the integrated brake controller comes standard from SLE up, a 120V outlet is standard from SLT, and AT4 and Denali can be ordered with the dent- and scratch-resistant CarbonPro carbon-fiber bed. Behind that sits GM's full accessory and upfit ecosystem.

A 24-gallon tank and 18 MPG combined give roughly 430 miles between stops — around 576 with the Duramax — and the truck tracks straight in a cabin reviewers single out as quiet, with a commanding view out and comfortable, supportive front seats. What keeps it mid-band is that adaptive cruise is optional package content so most buyers get no fatigue-reducing assist, IIHS rated every headlight variation Poor, which matters on a night drive, and the ride turns busy the moment the surface deteriorates.

Four-wheel drive is offered on every trim with a genuine two-speed transfer case and low range, and the AT4 pairs a 2-inch factory lift with Rancho monotube dampers, skid plates, an automatic locking rear differential, hill descent control and, new for 2021, Goodyear Wrangler Territory all-terrains. 2021 widened the reach further by adding the X31 Off-Road and Protection Package to SLE, Elevation and SLT. It is a capable gravel-road and trailhead vehicle with ample hitch and bed capacity for toys; short of a Raptor in articulation and clearance, and this model year has no AT4X.

A 62.9 cu ft open bed with 12 tie-downs and a six-function MultiPro tailgate that converts to a load stop, a step or a work surface is the most flexible loading arrangement in the segment, and it became standard on the volume trims this year. Inside, the rear bench flips up for a flat load floor and a lockable under-seat organizer is available; nearly every build leaves the factory with a hitch. It is not a perfect score because the bed is uncovered without an accessory tonneau, so secure weatherproof space is limited to the cab.

The fourth-generation T1 platform — fully boxed frame, independent front suspension, rear leaf axle — tracks straight and turns in more willingly than a 232-inch truck has any right to, and reviewers rate it poised for the class. The leaf-sprung rear is the ceiling: mid-corner bumps skip the axle and unsettle the truck where the coil-sprung Ram 1500 stays planted, and only the Denali's Adaptive Ride Control does anything about it.

The electric rack is accurate and naturally weighted enough to place the truck confidently in a highway lane, and reviewers credit its response and precision, but it passes essentially nothing back through the rim. Precise, stable and entirely numb — squarely mid-band, and unchanged from the generation's 2019 launch.

Four-wheel discs haul the 5,000-plus-pound Crew Cab down predictably and linearly, with no regen blending to complicate modulation, and an integrated trailer brake controller is standard from SLE up. Pedal quality is the reservation for this era of GM truck — long travel and soft feedback at the top of the stroke — so it is sufficient for daily use and towing rather than confidence-inspiring.

The 5.3L EcoTec3 V8 delivers smooth, abundant low-end torque with crisp tip-in — reviewers call the acceleration properly brisk — and the 3.0L Duramax is unusually refined for a diesel six. It lands below the later model years because 2021 is the most transmission-fragmented year of this generation, with the volume SLE and Elevation specifically demoted from the 10-speed to the 8-speed, and because Dynamic Fuel Management transitions are audible and occasionally rough at light throttle.

The small-block V8 makes a pleasant throaty growl under throttle and recedes to near-silence at a cruise in a cabin reviewers single out as quiet, and the Duramax stays civil. The mid-band placement reflects the pre-TurboMax 2.7L turbo four, which reviewers consistently describe as coarse at the revs a loaded truck actually uses, and the faint driveline shudder some owners report at light-throttle cylinder-deactivation transitions.

Roughly 46 ft to swing around is mid-band for a full-size truck and unchanged across the fourth generation — tighter than an F-150 SuperCrew's 47.8 ft and effectively level with the Ram 1500. The longer-wheelbase Crew Cab Standard Box pushes toward 50 ft and is noticeably harder to place.

The commanding H-point and real knobs with hard climate buttons are genuine assets, and the Sierra reaches a good driving position on cheaper trims than its Chevrolet twin — a power-adjustable driver's seat and a heated tilt/telescoping wheel are standard from SLE. It stays mid-band because 2021 is the last year of the criticized pre-refresh cabin: several controls are an awkward reach, the tall broad hood hides the road immediately ahead, over-the-shoulder visibility in the Crew Cab is a recurring complaint, and step-in is high without the optional power-assist steps.

The volume SLE/Elevation 5.3L is a competent, comfortable workhorse rather than a truck anyone takes the long way home in — the V8 soundtrack is the main source of character, and reviewers describe it as enjoyable despite the firm ride. The 420-hp 6.2L is genuinely quick at around 6.2 seconds to 60 mph in Denali form and the AT4 has off-road charm, but neither is what most 2021 buyers drove home, and this model year predates the Multimatic-damped AT4X.

2021 was a real content year at the bottom of the ladder: the six-function MultiPro tailgate became standard on every trim except the base Sierra (it was not offered at all in 2020), wireless Apple CarPlay and Android Auto arrived, and ProGrade Trailering came standard from SLE up. What holds the score down is driver assistance — forward collision alert, automatic emergency braking, front pedestrian braking and lane keep assist were all merely *available* for 2021, where the rival F-150 shipped Co-Pilot360 standard across the line; GMC did not make the Pro Safety package standard until the refreshed 2022 Sierra.

The Sierra carries roughly a $1,500–$3,000 premium over a comparably equipped Silverado on identical mechanicals, and the buyer gets genuine hardware for it — the MultiPro tailgate no rival matched, the carbon-fiber CarbonPro bed on AT4/Denali, ProGrade Trailering with its camera suite, a factory-lifted AT4 off-road trim, and five engines including the 2.7L Turbo and 3.0L Duramax. Against that, reviewers kept flagging a drab dashboard and ordinary materials at prices that reach deep into luxury territory, which is exactly where the value argument stops.

Six trims spanning roughly $31,800 to $61,300 delivered, three cab styles, three bed lengths and five engines from the 4.3L V6 through the 2.7L Turbo, 5.3L and 6.2L V8s to the 3.0L Duramax diesel — a wide, well-spaced ladder with a distinct off-road (AT4) and luxury (Denali) branch at the top. Only the F-150 and the Sierra's own Silverado sibling, with eight trims, offered more granularity at the work-truck end.

A consistent top-five US nameplate that essentially held its ground through the chip shortage — 248,923 US deliveries in 2021, off just 1.6% from the 2020 peak while the Silverado fell double digits — and, paired with the Silverado, delivered GM its second consecutive year of full-size pickup sales leadership. It is not a segment leader on its own badge, sitting behind the F-Series, Ram and Silverado.

GMC is General Motors' premium truck badge by design, and the Sierra is the vehicle that proves it: Denali accounts for roughly a third of Sierra volume, and GMC's Q4 2021 Sierra average transaction price of $63,181 was among the highest in the full-size class. That aspirational positioning is what separates it from the mechanically identical Silverado on both image and residuals.

Two completely different markets inside one model year. Through spring 2021 GMC was stacking real money on the hood — up to $7,900 off in March, 0% APR for 72 months, $250 competitive cash and a $239/month Elevation Crew Cab lease — but the semiconductor shortage idled the truck plants and by the fourth quarter GM had cut incentive spending by roughly two-thirds, with Sierras routinely transacting at or above sticker. A buyer's experience depended almost entirely on when in the year they walked in.

Third model year of the fourth generation launched for 2019, and a genuine content year rather than a carry-over — MultiPro tailgate standard on all but the base trim, the 10-speed automatic extended to 4WD 5.3L models, wireless smartphone mirroring, AT4 high-clearance steps, new 22-inch wheels and an illuminated grille emblem. But the widely criticized dashboard was entering its third year, and GMC revealed the heavily refreshed 2022 Sierra with its new cabin, 13.4-inch screen and Denali Ultimate in October 2021 — so a late-model-year buyer knowingly took the outgoing interior.

Well reviewed but never the class pick: praised for a quiet, comfortable, smooth-riding cabin, the MultiPro tailgate and a genuinely broad engine range, and marked down in nearly every comparison for a dash reviewers called drab across all trims and for materials that fall short of the Ram 1500 at the money. Its meaningful 2021 hardware was KBB's Best Resale Value recognition rather than a comparison-test win; North American Truck of the Year that season went to the redesigned F-150.