The GMC Sierra 2500HD, specifically the V (GMTT1XX) facelift model introduced in 2024, represents GMC’s heavy-duty full-size pickup truck offering. This iteration, featuring a Double Cab Long Bed configuration paired with the 6.6-liter Duramax Turbo Diesel V8 engine producing 470 horsepower, began production in 2023. It occupies a significant position within the 2500HD lineup, catering to buyers requiring substantial towing and hauling capabilities without sacrificing a degree of refinement. The GMTT1XX platform, a further evolution of the GMT1XX series, underpins this model, incorporating updated styling, technology, and enhanced mechanical components.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD V (GMTT1XX, facelift 2024) Double Cab Long Bed |
| Type (Engine) | 6.6 Duramax TD V8 (470 Hp) 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 | 7.1 kg/Hp, 141.1 Hp/tonne |
| Weight-to-torque ratio | 2.5 kg/Nm, 397 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 capacity | 28.5 l (30.12 US qt | 25.08 UK qt) |
| Kerb Weight | 3330 kg (7341.39 lbs.) |
| Max. weight | 4944 kg (10899.65 lbs.) |
| Max load | 1614 kg (3558.26 lbs.) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 8119 kg (17899.33 lbs.) |
| Length | 6534 mm (257.24 in.) |
| Width including mirrors | 2079 mm (81.85 in.) |
| Height | 2027 mm (79.8 in.) |
| Wheelbase | 4127 mm (162.48 in.) |
| Front track | 1731 mm (68.15 in.) |
| Rear track | 1736 mm (68.35 in.) |
| Ride height (ground clearance) | 257 mm (10.12 in.) |
| Drivetrain Architecture | Rear wheel drive |
| 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 2024 GMC Sierra 2500HD Double Cab Long Bed with the 6.6L Duramax diesel and 10-speed Allison automatic transmission is a workhorse designed for demanding tasks. Positioned as a mid-to-high range offering within the 2500HD lineup, it bridges the gap between the base gasoline engine options and the more specialized, higher-trim configurations. Built on the GMTT1XX platform, this truck benefits from significant updates to the exterior, interior, and technology compared to previous generations. It’s primarily targeted towards owners who frequently tow large trailers, haul heavy loads, and require a robust, reliable vehicle for both work and personal use. The Double Cab configuration provides increased passenger space compared to the Regular Cab, while the Long Bed offers ample cargo capacity.
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, renowned for its durability and 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 high-pressure common rail direct fuel injection system, delivering fuel directly into the cylinders at extremely high pressures for optimized combustion. The engine features an overhead valve (OHV) valvetrain, a design choice prioritizing low-end torque and reliability. A variable geometry turbocharger with an intercooler maximizes power and efficiency across the engine’s operating range. 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 when towing or hauling heavy loads.
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 driving experience focused on capability rather than outright speed. Acceleration is brisk, especially when considering the truck’s substantial weight. The 10-speed transmission allows the engine to remain in its optimal power band, providing strong pulling power at all speeds. Compared to the gasoline engine options, the diesel offers significantly more low-end torque, making it ideal for towing and hauling. While the gasoline engines may feel more responsive in everyday driving, the Duramax excels when subjected to heavy loads. The gear ratios in the Allison transmission are carefully chosen to balance fuel efficiency and towing performance. The truck feels planted and stable, even when fully loaded, thanks to its heavy-duty suspension and robust chassis.
Equipment & Trim Levels
The 2500HD Double Cab Long Bed with the Duramax engine typically comes standard with a comprehensive suite of features. These 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, such as Denali, add premium features like 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 a bed liner. The interior design emphasizes functionality and durability, with comfortable seating and intuitive controls.
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 towing heavy loads. The ABS (Anti-lock Braking System) helps maintain control during emergency braking situations. The steering system utilizes a hydraulic power steering setup, providing a responsive and precise steering feel.
Market Reception & Comparison
The GMC Sierra 2500HD with the Duramax diesel engine has consistently received positive reviews from automotive critics. It is praised for its powerful engine, smooth transmission, and impressive towing and hauling capabilities. Compared to its competitors, such as the Ford Super Duty and Ram 2500, the Sierra 2500HD often stands out for its refined interior and advanced technology features. Fuel economy, while not a primary concern for heavy-duty truck buyers, is generally competitive with other diesel-powered trucks in its class. Reliability has been generally good, although diesel engines can be more expensive to maintain than gasoline engines due to the complexity of the fuel injection system and emissions control components.
Legacy
The L5P Duramax engine has established a strong reputation for long-term reliability and durability. With proper maintenance, these engines can easily exceed 200,000 miles. The 10-speed Allison transmission has also proven to be a robust and reliable unit. In the used car market, Sierra 2500HD models equipped with the Duramax engine and Allison transmission command a premium price due to their proven performance and longevity. These trucks remain highly sought after by owners who require a capable and dependable workhorse for years to come.
