The GMC Sierra 2500HD, specifically the V (GMTT1XX) facelift model produced from 2023 onwards, represents GMC’s heavy-duty full-size pickup truck offering. This variant, configured as a Double Cab with a Standard Bed and powered by the 6.6-liter Duramax Turbo Diesel V8 engine producing 470 horsepower, occupies a significant position within the 2500HD lineup. It’s designed for buyers needing substantial towing and payload capacity without sacrificing everyday usability. The GMTT1XX platform, a refreshed version of the previous GMTK20, brings updated styling, technology, and enhanced capabilities to the heavy-duty segment.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD V (GMTT1XX, facelift 2024) Double Cab Standard Bed |
| Type (Engine) | 6.6 Duramax TD V8 (470 Hp) 4WD Automatic |
| Start of production | 2023 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 7.3 kg/Hp, 136.7 Hp/tonne |
| Weight-to-torque ratio | 2.6 kg/Nm, 384.6 Nm/tonne |
| Power | 470 Hp @ 2800 rpm |
| Power per litre | 71.2 Hp/l |
| Torque | 1322 Nm @ 1600 rpm (975.06 lb.-ft. @ 1600 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | L5P |
| Engine displacement | 6604 cm3 (403 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 103 mm (4.06 in.) |
| Piston Stroke | 99 mm (3.9 in.) |
| Compression ratio | 16:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Valvetrain | OHV |
| Engine oil capacity | 9.5 l (10.04 US qt | 8.36 UK qt) |
| Coolant | 28.5 l (30.12 US qt | 25.08 UK qt) |
| Kerb Weight | 3437 kg (7577.29 lbs.) |
| Max. weight | 4990 kg (11001.07 lbs.) |
| Max load | 1553 kg (3423.78 lbs.) |
| Fuel tank capacity | 111 l (29.32 US gal | 24.42 UK gal) |
| Permitted trailer load with brakes (12%) | 6577 kg (14499.8 lbs.) |
| Length | 6127 mm (241.22 in.) |
| Width including mirrors | 2079 mm (81.85 in.) |
| Height | 2031 mm (79.96 in.) |
| Wheelbase | 3795 mm (149.41 in.) |
| Front track | 1731 mm (68.15 in.) |
| Rear (Back) track | 1736 mm (68.35 in.) |
| Ride height (ground clearance) | 258 mm (10.16 in.) |
| Drivetrain Architecture | All wheel drive (4×4). ICE drives rear wheels, front engaged via clutch. |
| Number of gears and type of gearbox | 10 gears, automatic transmission Allison |
| Front suspension | Independent torsion bar, double wishbone |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs, 350×40 mm |
| Rear brakes | Ventilated discs, 360×34 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Power steering | Hydraulic Steering |
| Tires size | 235/80 R17; 265/70 R17; 245/75 R17; 265/70 R18; 265/60 R20 |
| Wheel rims size | 7.5J x 17; 8J x 18; 8.5J x 20 |
Introduction
The 2023+ GMC Sierra 2500HD Double Cab Standard Bed with the 6.6L Duramax diesel and 10-speed Allison automatic transmission is a workhorse pickup truck designed for demanding tasks. Positioned as a mid-to-high trim level within the 2500HD range, it offers a balance between capability, comfort, and technology. The facelifted GMTT1XX generation brought significant updates to the exterior styling, interior refinement, and available technology features, enhancing the Sierra 2500HD’s appeal in the competitive heavy-duty truck market. This configuration caters to owners who frequently tow large trailers, haul heavy loads, or require a robust vehicle for commercial or personal use.
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD lies the L5P 6.6-liter Duramax turbocharged diesel V8 engine. This engine is a cornerstone of GMC’s heavy-duty lineup, known for its durability and impressive torque output. The L5P utilizes a cast iron block, aluminum cylinder heads, and a robust crankshaft designed to withstand the stresses of heavy-duty operation. It employs a diesel commonrail fuel injection system, delivering precise fuel metering for optimal combustion and efficiency. The turbocharger, coupled with an intercooler, provides increased air intake, boosting power and torque. The engine features an overhead valve (OHV) valvetrain, a design choice prioritizing low-end torque and reliability. The 10-speed Allison automatic transmission is specifically calibrated to handle the engine’s substantial torque, providing smooth and efficient power delivery. This transmission features electronically controlled shifts and multiple tow/haul modes to optimize performance for various driving conditions.
Driving Characteristics
The combination of the 470 horsepower and 975 lb-ft of torque delivered by the Duramax engine and the 10-speed Allison transmission results in a powerful and capable driving experience. While not as quick off the line as gasoline-powered counterparts, the Sierra 2500HD excels in situations requiring substantial pulling power. The 10-speed transmission keeps the engine within its optimal power band, providing strong acceleration even when towing heavy loads. Compared to lower-output gasoline engine options, this Duramax variant offers significantly more torque, making it ideal for demanding tasks. Compared to the 6.6L gasoline engine, the diesel provides a more relaxed driving experience when towing, with less need for frequent downshifts. The ride quality, while firm due to the heavy-duty suspension, is surprisingly comfortable for a truck of this size.
Equipment & Trim Levels
The specific standard equipment varies depending on the chosen trim level (SLE, Elevation, AT4, Denali, etc.). However, common features on this variant typically include air conditioning, power windows and locks, a touchscreen infotainment system with Apple CarPlay and Android Auto compatibility, and a rearview camera. Higher trim levels add features such as leather upholstery, heated and ventilated seats, a premium sound system, and advanced safety technologies like adaptive cruise control and lane departure warning. Optional extras include a power sunroof, a navigation system, and various towing packages. The Double Cab configuration provides comfortable seating for five passengers, while the Standard Bed offers a practical cargo-carrying capacity.
Chassis & Braking
The Sierra 2500HD utilizes a body-on-frame construction, providing a robust and durable platform for heavy-duty applications. The front suspension features an independent torsion bar setup with double wishbones, offering a comfortable ride and good handling. The rear suspension employs a traditional leaf spring design, optimized for load-carrying capacity. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power even when heavily loaded. The ABS (Anti-lock Braking System) enhances safety by preventing wheel lockup during hard braking. Hydraulic power steering provides responsive and precise steering control.
Market Reception & Comparison
The GMC Sierra 2500HD with the Duramax diesel engine has consistently received positive reviews for its towing capacity, reliability, and overall performance. Critics praise the engine’s robust power delivery and the Allison transmission’s smooth operation. Compared to competitors like the Ford Super Duty and Ram 2500, the Sierra 2500HD often stands out for its refined interior and available technology features. Fuel economy, while not a primary concern for heavy-duty truck buyers, is respectable for a vehicle of this size and capability. The Duramax diesel generally offers better fuel economy than the gasoline engine options, particularly when towing. Reliability has been generally good, with the Duramax engine proving to be a durable and long-lasting powerplant.
Legacy
The L5P Duramax engine has established a strong reputation for reliability and longevity. Properly maintained, these engines can easily exceed 200,000 miles. On the used car market, Sierra 2500HD models equipped with this powertrain hold their value well due to their proven capabilities and durability. The 10-speed Allison transmission has also proven to be a reliable component, further enhancing the long-term appeal of this configuration. The GMTT1XX facelifted models are expected to continue to be sought after for years to come, offering a compelling combination of power, capability, and refinement in the heavy-duty truck segment.
