The GMC Sierra 2500HD IV (GMTK2XX) Double Cab Standard Box with the 6.0L V8 engine and automatic transmission, produced from 2015 to 2016, represented a significant offering in the heavy-duty pickup truck segment. This variant, often equipped with a Compressed Natural Gas (CNG) system, aimed to balance power, capability, and alternative fuel efficiency for both commercial and personal use. It occupied a mid-range position within the Sierra 2500HD lineup, offering a step up in power and towing capacity from the base models while remaining more accessible than the diesel-powered options.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD IV (GMTK2XX) Double Cab Standard Box |
| Type (Engine) | 6.0 V8 (301 Hp) Automatic CNG |
| Start of production | 2015 |
| End of production | 2016 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol / CNG |
| Power | 301 Hp @ 5000 rpm |
| Power per litre | 50.4 Hp/l |
| Torque | 452 Nm @ 4200 rpm / 333.38 lb.-ft. @ 4200 rpm |
| Maximum engine speed | 6000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Vortec LC8 |
| Engine displacement | 5967 cm3 / 364.13 cu. in. |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 101.6 mm / 4 in. |
| Piston Stroke | 92 mm / 3.62 in. |
| Compression ratio | 9.6:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | OHV, VVT |
| Engine oil capacity | 5.7 l / 6.02 US qt | 5.02 UK qt |
| Coolant | 15.5 l / 16.38 US qt | 13.64 UK qt |
| Fuel tank capacity | 136 l / 35.93 US gal | 29.92 UK gal |
| CNG cylinder capacity | 67 kg |
| Permitted trailer load with brakes (12%) | 4218 kg / 9299.1 lbs. |
| Length | 5842 mm / 230 in. |
| Width including mirrors | 2045 mm / 80.51 in. |
| Height | 1984 mm / 78.11 in. |
| Wheelbase | 3662 mm / 144.17 in. |
| Front track | 1748 mm / 68.82 in. |
| Rear (Back) track | 1709 mm / 67.28 in. |
| Ride height (ground clearance) | 218 mm / 8.58 in. |
| Minimum turning circle (turning diameter) | 15 m / 49.21 ft. |
| 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, 350×40 mm |
| Rear brakes | Ventilated discs, 360×34 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Tires size | 245/75 R17; 265/70 R17; 265/70 R18; 265/60 R20 |
| Wheel rims size | 7.5J x 17; 8J x 18; 8.5J x 20 |
INTRODUCTION
The 2015-2016 GMC Sierra 2500HD Double Cab Standard Box, powered by the 6.0-liter Vortec LC8 V8 engine and a six-speed Hydra-Matic automatic transmission, was a key component of GMC’s fourth-generation heavy-duty truck lineup (GMTK2XX platform). This generation represented a significant leap forward in terms of refinement, capability, and technology compared to its predecessors. The Double Cab configuration offered a balance between passenger space and bed length, making it suitable for both work and family needs. The availability of a CNG conversion added a unique dimension, appealing to fleets and individuals seeking to reduce their reliance on gasoline and lower emissions.
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD variant lies the 6.0-liter Vortec LC8 V8 engine. This engine is a naturally aspirated, overhead valve (OHV) design featuring variable valve timing (VVT) for improved efficiency and performance. The LC8 utilizes multi-port fuel injection, delivering fuel directly to each cylinder. The engine produces 301 horsepower at 5000 rpm and 360 lb-ft of torque at 4200 rpm. The engine’s robust construction and relatively simple design contribute to its reputation for reliability. The six-speed Hydra-Matic automatic transmission was specifically tuned to handle the engine’s torque output and the demands of heavy towing and hauling. The CNG system, when equipped, typically operates in a bi-fuel configuration, allowing the truck to seamlessly switch between gasoline and CNG depending on fuel availability and driver preference.
Driving Characteristics
The 6.0L V8 and automatic transmission combination provided a comfortable and capable driving experience. While not as quick as some of the diesel-powered alternatives, the LC8 offered ample power for everyday driving and towing. The automatic transmission’s gear ratios were optimized for both hauling and highway cruising. Compared to the manual transmission versions, the automatic provided smoother shifts and reduced driver fatigue, particularly in stop-and-go traffic. However, the automatic did result in a slight reduction in fuel economy compared to the manual. The CNG system, when engaged, slightly reduced power output but offered lower fuel costs and reduced emissions. Overall, the driving experience was characterized by a smooth ride and a confident feel, even when carrying heavy loads.
Equipment & Trim Levels
The Sierra 2500HD Double Cab Standard Box 6.0L Automatic typically came standard with features such as air conditioning, power windows and locks, a basic audio system, and a tilt steering wheel. Higher trim levels, such as the SLE and SLT, added features like leather upholstery, heated seats, a premium audio system, navigation, and a rearview camera. Optional extras included a trailer brake controller, a locking rear differential, and various appearance packages. The interior design was functional and durable, with a focus on providing a comfortable and practical work environment. The Double Cab configuration offered ample space for five passengers, making it a versatile option for families and crews.
Chassis & Braking
The Sierra 2500HD featured a robust chassis designed to withstand the stresses of heavy-duty use. The front suspension utilized coil springs and a double wishbone design, while the rear suspension employed a traditional leaf spring setup. This configuration provided a good balance between ride comfort and load-carrying capacity. Braking duties were handled by ventilated disc brakes on all four wheels, with ABS (Anti-lock Braking System) as standard equipment. The braking system was adequately sized for the truck’s weight and towing capacity. Stabilizer bars were included to reduce body roll during cornering.
Market Reception & Comparison
The 2015-2016 GMC Sierra 2500HD 6.0L Automatic received generally positive reviews. Critics praised its comfortable ride, spacious interior, and capable powertrain. The CNG option was seen as a positive step towards alternative fuel adoption, although its limited refueling infrastructure was a concern for some. Compared to the diesel-powered Sierra 2500HD models, the 6.0L V8 offered a lower initial cost but less torque and lower fuel economy when operating on gasoline. Compared to competitors like the Ford Super Duty and Ram 2500, the Sierra 2500HD was considered to be competitive in terms of features, capability, and price.
Legacy
The Vortec LC8 6.0L V8 engine, paired with the Hydra-Matic transmission, has proven to be a relatively reliable powertrain. While not without its potential issues (such as Active Fuel Management system problems in some cases), the engine is generally known for its durability and longevity. In the used car market, these Sierra 2500HD models remain popular choices for those seeking a capable and affordable heavy-duty truck. The CNG-equipped versions are particularly sought after by those looking to reduce their fuel costs and environmental impact. The GMTK2XX platform Sierra 2500HD represents a solid and dependable truck that continues to provide years of service for many owners.
