The GMC Sierra 3500HD, specifically the V (GMTT1XX) Double Cab Long Bed configuration powered by the 6.6-liter V8 engine producing 401 horsepower, represents a significant offering in the heavy-duty pickup truck segment. Produced from 2020 through 2023, this variant catered to buyers needing substantial towing and payload capacity, bridging the gap between work-focused trucks and those desiring more passenger space than a regular cab offered. It occupied a mid-to-upper position within the Sierra 3500HD lineup, offering a balance of capability and comfort, and was a key component of GMC’s strategy to compete with Ford and Ram in the increasingly popular heavy-duty truck market.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD V (GMTT1XX) Double Cab Long Bed |
| Type (Engine) | 6.6 V8 (401 Hp) DRW Automatic |
| Start of production | 2020 |
| End of production | 2023 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 7.9 kg/Hp, 126.7 Hp/tonne |
| Weight-to-torque ratio | 5 kg/Nm, 198.7 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, VVT |
| 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 | 3165 kg (6977.63 lbs) |
| Max. weight | 6350 kg (13999.35 lbs) |
| Max load | 3185 kg (7021.72 lbs) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 7439 kg (16400.19 lbs) |
| Length | 6514 mm (256.46 in) |
| Width including mirrors | 2457 mm (96.73 in) |
| Height | 2037 mm (80.2 in) |
| Wheelbase | 4127 mm (162.48 in) |
| Front track | 1731 mm (68.15 in) |
| Rear (Back) track | 1905 mm (75 in) |
| Ride height (ground clearance) | 264 mm (10.39 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 | 6 gears, automatic transmission Hydra-Matic |
| Front suspension | Coil spring, Double wishbone, Transverse stabilizer |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs, 355×40 mm |
| Rear brakes | Ventilated discs, 355×40 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; 275/70 R18 |
| Wheel rims size | 7.5J x 17; 8J x 18 |
INTRODUCTION
The GMC Sierra 3500HD V (GMTT1XX) Double Cab Long Bed 6.6 V8 (401 Hp) DRW Automatic, introduced for the 2020 model year and continuing through 2023, is a heavy-duty pickup truck designed for demanding tasks. Built on the GMTT1XX platform, this generation Sierra 3500HD represented a significant update to GMC’s heavy-duty lineup, focusing on increased capability, improved interior refinement, and advanced technology. The “DRW” designation indicates a Dual Rear Wheel configuration, further enhancing its towing and hauling capacity. The Double Cab body style provided increased rear passenger space compared to the standard cab, making it suitable for crews or families. This particular variant, with its 401-horsepower 6.6-liter V8 and six-speed automatic transmission, aimed to deliver a balance of power, efficiency, and usability for a wide range of customers.
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD lies the L8T 6.6-liter naturally aspirated V8 engine. This engine utilizes direct fuel injection, a technology that improves fuel efficiency and power output by injecting fuel directly into the combustion chamber. The engine features an overhead valve (OHV) valvetrain with variable valve timing (VVT), optimizing engine performance across a wider range of engine speeds. The engine produces 401 horsepower at 5200 rpm and 629 Nm (463.93 lb-ft) of torque at 4000 rpm. This torque output is crucial for heavy towing and hauling. The engine is paired with a six-speed Hydra-Matic automatic transmission, chosen for its durability and ability to handle the engine’s substantial torque. The transmission is electronically controlled, offering smooth and precise shifting. The longitudinal engine layout and rear-wheel-drive configuration are standard for this type of heavy-duty truck.
Driving Characteristics
The 6.6-liter V8 and six-speed automatic combination in the Sierra 3500HD delivers a robust driving experience. While not as quick as some of the newer turbocharged engines found in competing trucks, the L8T provides ample power for everyday driving and demanding tasks. The automatic transmission is well-tuned, offering smooth shifts and responsive downshifts when needed. The gear ratios are optimized for towing, providing strong low-end torque. Compared to the diesel engine options available in the Sierra 3500HD lineup, this gasoline V8 offers a more refined and quieter driving experience, but sacrifices some fuel economy and ultimate towing capacity. Compared to a manual transmission equipped model, the automatic provides ease of use, especially in stop-and-go traffic or when towing heavy loads.
Equipment & Trim Levels
The Sierra 3500HD Double Cab Long Bed 6.6 V8 (401 Hp) DRW Automatic typically came standard with a comprehensive list of features. These included air conditioning, power windows and locks, a basic infotainment system with a touchscreen display, and a rearview camera. The Double Cab configuration offered comfortable seating for five passengers. Interior upholstery was typically cloth, with options for leather upgrades available on higher trim levels. Available options included a premium audio system, navigation, heated and ventilated front seats, and a variety of driver-assistance features such as lane departure warning and forward collision alert. Trim levels varied, with SLE and SLT being common designations, offering progressively more features and luxury appointments.
Chassis & Braking
The Sierra 3500HD’s chassis is built for durability and heavy-duty use. The front suspension utilizes a coil spring and double wishbone design with a transverse stabilizer bar, providing a comfortable ride and stable handling. The rear suspension employs a rigid axle with leaf springs, designed to handle heavy loads. The braking system features ventilated discs on all four wheels, measuring 355×40 mm, providing ample stopping power. An Anti-lock Braking System (ABS) is standard. The steering system is a cone worm with recirculation balls, offering precise control. The Dual Rear Wheel configuration significantly increases the truck’s stability and load-carrying capacity.
Market Reception & Comparison
The GMC Sierra 3500HD V (GMTT1XX) Double Cab Long Bed 6.6 V8 (401 Hp) DRW Automatic was generally well-received by critics and consumers. It was praised for its robust powertrain, comfortable interior, and impressive towing and hauling capabilities. However, some reviewers noted that the gasoline V8 engine’s fuel economy was lower than that of the diesel options. Compared to the diesel-powered Sierra 3500HD models, this variant offered a lower initial purchase price but higher operating costs due to fuel consumption. It also provided a quieter and more refined driving experience. Against competitors like the Ford Super Duty and Ram 3500, the Sierra 3500HD held its own, offering a compelling combination of features and performance.
Legacy
The L8T 6.6-liter V8 engine and Hydra-Matic transmission pairing in the Sierra 3500HD has proven to be a relatively reliable powertrain. While not without its potential issues (such as occasional active fuel management problems), the engine is generally considered durable and capable of lasting for many years with proper maintenance. In the used car market, these Sierra 3500HD models remain popular choices for buyers seeking a capable and affordable heavy-duty truck. The DRW configuration and Double Cab body style add to their appeal, making them suitable for a variety of applications, from work to recreation. The GMTT1XX platform Sierra 3500HD represents a solid and dependable option in the heavy-duty truck segment.
