It hasn’t even been a year since GMC launched its all-new 2020 Sierra HD, and yet we just found out exactly what’s in store for the second model year of the heavy duty pickup truck. Indeed, GMC is giving the Sierra 2500HD more than a handful of changes and updates, including to the exterior, interior, package structure, powertrain and even a few new features. GM Authority has compiled exactly what’s new and different for the 2021 GMC Sierra 2500HD, so let’s dive right in.
The 2021 GMC Sierra 2500HD trim level structure remains the same as for the 2020 models, with the Sierra being the base trim, followed by SLE, SLT, AT4 and Denali. We will reference these trim levels throughout this piece, and are providing a chart outlining the trim hierarchy so you can follow right along.
|Cab:||Regular, Double, Crew||Double, Crew||Crew|
|Trim Level:||Sierra (base)||SLE||SLT||AT4||Denali|
On the outside, the 2021 GMC Sierra 2500HD deletes two exterior colors and adds three new ones.
- Dark Sky Metallic
- Red Quartz Tintcoat
- Ebony Twilight Metallic
- Cayenne Red Tintcoat
- Hunter Metallic exterior paint
Additionally, there are various tailgate-related changes surrounding the SLE trim level. First, the GMC MultiPro tailgate becomes standard on the SLE model, and includes the manual tailgate with lift assist function. Those who prefer a more traditional tailgate instead can still get the standard/regular tailgate instead of the MultiPro.
Meanwhile, the offroad-oriented Sierra HD AT4 gains high-gloss black mirror caps as standard along with optional LPO-level (dealer-installed features) high clearance step.
The range-topping Denali model gains a new power-retractable assist step with LED perimeter lighting as an option. These steps are part of the Denali Black Diamond Edition edition package (more on that down below).
Two new LPO-level (dealer-installed) accessories for the bed are introduced:
- Right hand and left hand side bedside storage
- Four tie-downs
There are also all kinds of wheel changes, as follows:
- Deleted: 18-inch 6-spoke machined aluminum wheels with high gloss black accents extended (PYR)
- For the 2020 model year, these were available on SLE and standard on SLT and AT4
- Added: 18-inch machined aluminum wheel with Dark Grey metallic accents (PXD)
- Seemingly replacing the PYR wheels, these are available on SLE (as part of the X31 off-road and protection package) and standard on SLT and AT4
- 20-inch high gloss black painted aluminum wheels added (RTJ)
- Available only on Denali with Denali Black Diamond Edition package
- 20-inch Black Transit wheels are added (Q7Q) as LPO-level item
- Available only on AT4 and Denali
- 20-inch high gloss Black aluminum wheels with machined inserts (SKX) added as LPO-level item
- Available only on AT4 and Denali
- 20-inch multi-dimensional Chrome aluminum wheels added (SKW) as LPO-level item
- Available only on Denali
- The 20-inch machined aluminum wheels with bright Silver accents (Q7R) have a new finish
- These are optional on SLE and SLT
- The 20-inch machined aluminum wheels with high gloss Black accents (PYU) have a new finish
- These are included only on the optional AT4 Premium Plus package, available – you guessed it – only on the AT4
What’s more, the Sierra HD AT4 also gains new LT275/70R18, mud-terrain, blackwall tires as an option. These tires have a reduction in conventional trailering capacity. The standard tires on the AT4 remain the LT275/70R18E all-terrain, blackwall tires.
Finally, there is a small yet important change in the way the Gooseneck / 5th Wheel Package is ordered on the Denali trim level: rather than ordering the Gooseneck / 5th Wheel Package (CMT), dealers must now order the free flow option Gooseneck / 5th Wheel Prep Package (Z6A) on the Denali trim.
Inside, the 2021 GMC Sierra 2500HD sees the introduction of a new inside rearview auto-dimming mirror with partial video display. The new mirror shows the video feed of the cargo bed, captured by an equally-new Bed View Camera, which is located in the CHMSL. The features are available on Sierra base (1SA) and SLE (3SA). Not opting for these features equips these two models with the standard inside rearview mirror with a manual tilt feature. Another alternative to the new Bed View Camera mirror is an inside rearview mirror with auto-dimming capability. It’s worth noting that the Bed View Camera was around for the 2020 model year on SLE, SLT, AT4 and Denali models. However, the output on these models was shown on the center screen, rather than in the rearview mirror. As such, it would seem that the new auto-dimming mirror with a partial video display is a lower-cost way of giving lower-end models the Bed View Camera ability.
Furthermore, the 2021 Sierra 2500HD also gets wireless Apple CarPlay and Android Auto functionality, joining a growing list of 2021 model year GM vehicles with the wireless phone projection capability. which – as we opined last year – was badly needed. SiriusXM, meanwhile, becomes available on the base model and available on SLE. For the 2020 model year, it was not available on the base model while being optional on SLE. But unlike higher-end models, this version of SiriusXM capability does not include SiriusXM 360L, which remains reserved as a standard feature for SLT, AT4 and Denali models. Those opting for the SLE trim can now get the SiriusXM with 360L capability by opting for the Preferred Package or the ProGrade Trailering System.
The SLE trim level is no longer available with bucket seats. The trim now ships standard with 40/20/40 split-bench front seats with covered armrest storage. Customers can also upgrade to the same seating configuration but with lockable under-seat storage as part of a package. Those desiring front bucket seats will need to upgrade to the SLT, AT4 or Denali trims.
Additionally, the base model gets two a rubberized-vinyl floor covering as standard, while color-keyed carpeting becomes available. The Sierra 2500HD also gets a new set of available premium front or rear floor liners with removable carper inserts. These are available on SLT and Denali, while being standard on AT4.
Speaking of seats, the base model deletes the front 40/20/40 split-bench seat without storage, and replaces it with front 40/20/40 split-bench seat with upper covered armrest storage. On the 2020 model year, the 40/20/40 split-bench seat with upper covered armrest storage was not available on the base model, but was standard on the SLE model in Crew Cab and Double Cab. The base model also deletes the single USB port located on the instrument panel, and replaces it with a double USB port on the instrument panel. On the 2020 model year, the dual USB port was standard only on the SLE and available on SLT models.
The 2021 GMC Sierra 2500HD also gets a whole bunch of package-level changes, with two packages deleted, six packages added, and seven changes, to boot. Here goes:
- SLT Premium Plus Package
- Texas Edition SLT Premium Plus Package
- Safety Essentials Package
- SLT Premium Package
- Texas Edition SLT Premium Package
- AT4 Premium Plus Package
- Denali Black Diamond Edition; package requires 4WD models and includes:
- Auxiliary Trailer Camera
- MultiPro Audio System by Kicker
- Front floor liners with removable carpet insert
- Rear floor liners with removable carpet insert
- Trailer tire pressure monitor sensors
- Power-retractable assist steps with LED perimeter lighting
- 20-inch high gloss Black painted aluminum wheels
- X31 Off-Road and Protection Package
Changes to packages:
- Bed View Camera is now included in SLT Preferred Package and AT4 Preferred Package
- HD Surround Vision with Two Trailer View Camera Provisions is now included in SLT Preferred Package and AT4 Preferred Package
- SLE Convenience Package no longer includes EZ Lift power lock and release tailgate
- SLT Preferred Package now includes Bed View Camera and HD Surround Vision with Two Trailer View Camera Provisions
- AT4 Preferred Package now includes Bed View Camera and HD Surround Vision with Two Trailer View Camera Provisions
- Technology Package no longer includes Bed View Camera or HD Surround Vision
- ProGrade Trailering System no longer includes Sirius XM and EZ Lift and power lock and release tailgate
Only one mechanical change is made to the 2021 GMC Sierra 2500HD, and it’s a pretty important one: the addition of optional E85 FlexFuel capability for the new 6.6L V8 L8T gasoline engine. This option is available only on the Sierra base (1SA) model, requires the JL1 trailer brake controller and is not available with the pickup box delete option. Selecting this option on the Regular Cab models requires the Convenience Package.
The L8T gasoline engine remains the standard motor in the Sierra HD. It’s mated to the GM six-speed automatic transmission. Maximum output is rated at 401 horsepower and 464 pound-feet of torque.
Having launched for the 2020 model year, 2021 represents the all-new Sierra HD’s second year on the market. We expect the vehicle to remain in its current form for the 2021 and 2022 model years. For the 2023 model year, we expect the entire Sierra HD line to receive a mid-cycle enhancement (MCE/refresh), complete with a redesigned interior about which GM Authority was first to report. These changes will make their way to the Sierra 1500 for the 2022 model year.