The GMC Sierra 2500HD, in its fifth generation (GMTT1XX), underwent a significant refresh for the 2024 model year. This article focuses specifically on the Double Cab Standard Bed configuration equipped with the 6.6-liter V8 gasoline engine producing 401 horsepower, paired with a 10-speed automatic transmission. Introduced in 2023 with the facelift, this variant represents a balance between capability and everyday usability within the Sierra 2500HD lineup, targeting buyers needing heavy-duty towing and hauling without the extreme bulk of the crew cab models.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD V (GMTT1XX, facelift 2024) Double Cab Standard Bed |
| Type (Engine) | 6.6 V8 (401 Hp) Automatic |
| Start of production | 2023 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 7.4 kg/Hp, 134.3 Hp/tonne |
| Weight-to-torque ratio | 4.7 kg/Nm, 210.7 Nm/tonne |
| Power | 401 Hp @ 5200 rpm |
| Torque | 629 Nm @ 4000 rpm (463.93 lb.-ft. @ 4000 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | L8T |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 103.25 mm (4.06 in) |
| Piston Stroke | 98 mm (3.86 in) |
| Compression ratio | 10.8:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Direct injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | OHV |
| Engine oil capacity | 7.6 l (8.03 US qt | 6.69 UK qt) |
| Coolant | 14.6 l (15.43 US qt | 12.85 UK qt) |
| Kerb Weight | 2985 kg (6580.8 lbs) |
| Max. weight | 4559 kg (10050.87 lbs) |
| Max load | 1574 kg (3470.08 lbs) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 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 | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | 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, 355×40 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 | 245/75 R17; 265/70 R17; 275/70 R18; 275/65 R20 |
| Wheel rims size | 7.5J x 17; 8J x 18; 8.5J x 20 |
INTRODUCTION
The 2024 GMC Sierra 2500HD Double Cab Standard Bed with the 6.6L V8 and 10-speed automatic represents GMC’s offering in the heavy-duty pickup segment. Positioned within the broader GMTT1XX generation, which debuted in 2020 and received a substantial facelift for 2024, this configuration caters to customers who require substantial towing and payload capacity but don’t necessarily need the larger interior space of the crew cab. The Double Cab provides seating for five and a shorter bed length, making it more maneuverable than its larger sibling. This variant is primarily sold in the North American market, where full-size, heavy-duty trucks are exceptionally popular.
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD is the L8T 6.6-liter naturally aspirated V8 gasoline engine. This engine utilizes direct fuel injection, a hallmark of modern gasoline engine design, to improve efficiency and power output. The engine features an overhead valve (OHV) valvetrain, a traditional design choice for heavy-duty truck engines prioritizing durability and low-end torque. The 10-speed Allison automatic transmission is a key component, providing a wide gear ratio spread for optimal towing and hauling performance. This transmission is known for its robustness and smooth shifting characteristics. The engine produces 401 horsepower at 5200 rpm and 629 lb-ft of torque at 4000 rpm, providing ample power for demanding tasks. The engine oil capacity is 7.6 liters (8.03 US quarts), and requires a specific oil specification for optimal performance and longevity.
Driving Characteristics
The 6.6L V8 and 10-speed automatic combination delivers a robust and confident driving experience. While not as quick as some of the newer turbocharged engines found in competing trucks, the L8T provides a strong low-end torque curve, making it well-suited for towing and hauling heavy loads. The 10-speed transmission allows the engine to stay within its optimal power band, even when climbing hills or accelerating with a trailer. Compared to the available Duramax diesel engine, this gasoline V8 offers a quieter and smoother ride, but sacrifices fuel economy and ultimate towing capacity. The gear ratios are tuned for work, prioritizing pulling power over outright acceleration. The Double Cab configuration, with its shorter wheelbase, offers slightly improved maneuverability compared to the crew cab models.
Equipment & Trim Levels
The 2500HD Double Cab Standard Bed with the 6.6L V8 typically comes standard with features such as a touchscreen infotainment system, Apple CarPlay and Android Auto compatibility, and a suite of safety features including automatic emergency braking. Trim levels vary, but generally include SLE, Elevation, and Denali. Higher trims like the Denali add premium features such as leather upholstery, heated and ventilated seats, a premium sound system, and advanced driver-assistance systems. Optional extras include a gooseneck hitch, bed liner, and various appearance packages. Interior upholstery typically ranges from cloth in the base SLE trim to leather in the higher Denali trim.
Chassis & Braking
The Sierra 2500HD utilizes a body-on-frame construction, providing a robust and durable platform for heavy-duty use. The front suspension features an independent torsion bar setup with double wishbones, while the rear suspension employs a traditional leaf spring design. This configuration is optimized for load-carrying capacity and stability. Braking duties are handled by ventilated discs at all four corners, with larger rotors at the front (355×40 mm) compared to the rear (360×34 mm). An Anti-lock Braking System (ABS) is standard. The steering system utilizes a cone worm with recirculation balls, providing a direct and responsive feel.
Market Reception & Comparison
Critics generally praised the 2024 Sierra 2500HD for its comfortable ride, spacious interior (particularly in the Double Cab), and strong towing capabilities. The 6.6L V8 engine received positive reviews for its smooth power delivery and reliability. However, some reviewers noted that the gasoline engine’s fuel economy lags behind that of the Duramax diesel. Compared to competitors like the Ford Super Duty and Ram 2500, the Sierra 2500HD offers a competitive combination of features, performance, and value. The gasoline engine variant is often favored by buyers who prioritize lower upfront cost and simpler maintenance over maximum towing capacity and fuel efficiency.
Legacy
The L8T 6.6L V8 engine has proven to be a reliable and durable powertrain in the Sierra 2500HD. While the diesel engine remains the preferred choice for heavy-duty towing, the gasoline V8 continues to be a popular option for buyers who don’t require the absolute maximum towing capacity. In the used car market, these models are generally well-regarded for their longevity and relatively straightforward maintenance requirements. The 10-speed Allison transmission has also proven to be exceptionally durable, contributing to the overall reliability of this powertrain combination. As of 2024, the GMTT1XX generation Sierra 2500HD continues to be a strong contender in the heavy-duty pickup truck segment.
