The GMC Sierra 2500HD IV, specifically the Regular Cab Long Box configuration with the 6.0L V8 engine (301 horsepower) paired with a 4WD automatic transmission and capable of running on Compressed Natural Gas (CNG), was produced for the 2015 and 2016 model years. This variant occupied a significant position within the fourth generation (GMTK2XX) of the Sierra 2500HD lineup, catering to buyers needing substantial towing and hauling capacity with the added flexibility of alternative fuel operation. It represented a work-focused trim, prioritizing capability over luxury, and served as a robust option for commercial users and individuals requiring a heavy-duty pickup.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD IV (GMTK2XX) Regular Cab Long Box |
| Type (Engine) | 6.0 V8 (301 Hp) 4WD Automatic CNG |
| Start of production | 2015 |
| End of production | 2016 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 2 |
| Doors | 2 |
| 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 | 5699 mm / 224.37 in. |
| Width including mirrors | 2035 mm / 80.12 in. |
| Height | 1975 mm / 77.76 in. |
| Wheelbase | 3393 mm / 133.58 in. |
| Front track | 1748 mm / 68.82 in. |
| Rear (Back) track | 1709 mm / 67.28 in. |
| Ride height (ground clearance) | 231 mm / 9.09 in. |
| Minimum turning circle (turning diameter) | 14 m / 45.93 ft. |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels permanently, and the front wheels are driven through an electrically or mechanically operated clutch if necessary. |
| Drive wheel | All wheel drive (4×4) |
| 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 |
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD variant lies the Vortec LC8 engine, a 6.0-liter (364.13 cubic inches) V8. This engine is a member of the Vortec family, known for its robust construction and relatively simple design. It features a cast iron block and aluminum cylinder heads. The LC8 utilizes a multi-port fuel injection system, delivering fuel to each cylinder individually for optimized combustion. The overhead valve (OHV) valvetrain, coupled with variable valve timing (VVT), helps to balance power delivery and fuel efficiency. The engine produces 301 horsepower at 5000 rpm and 452 Nm (333.38 lb-ft) of torque at 4200 rpm. The Hydra-Matic 6-speed automatic transmission was the sole transmission option for this configuration. This transmission is known for its durability and smooth shifting characteristics, although it isn’t the most technologically advanced automatic available at the time. The inclusion of CNG capability allowed operators to take advantage of potentially lower fuel costs and reduced emissions, though it required dedicated CNG fueling infrastructure.
Driving Characteristics
The 6.0L V8 and 6-speed automatic combination in the Sierra 2500HD delivered a capable, if not particularly sporty, driving experience. The emphasis was squarely on work capability. The torque output of 333.38 lb-ft provided ample power for towing and hauling heavy loads. However, compared to the available Duramax diesel engine, the gasoline V8 offered less low-end grunt. The automatic transmission’s gear ratios were optimized for towing, resulting in a relatively conservative feel during everyday driving. Acceleration was adequate, but not brisk. The 4WD system provided enhanced traction in challenging conditions, making it suitable for both on- and off-road use. Compared to a manual transmission equipped Sierra 2500HD, the automatic offered greater convenience, especially in stop-and-go traffic, but at the expense of some driver control and potentially slightly reduced fuel economy.
Equipment & Trim Levels
The Regular Cab Long Box 6.0L CNG variant of the Sierra 2500HD typically represented a work-truck focused trim level. Standard features generally included a basic audio system, vinyl upholstery, air conditioning, and power windows and locks. The interior was functional and durable, prioritizing practicality over luxury. Options available included upgraded audio systems, power seats, and various towing packages. The exterior typically featured black bumpers and side moldings, reflecting its work-oriented nature. CNG-specific components, such as the CNG fuel tank and related plumbing, were integrated into the vehicle’s chassis.
Chassis & Braking
The Sierra 2500HD’s chassis was built for heavy-duty use. The front suspension utilized a coil spring and double wishbone setup with a transverse stabilizer bar, while the rear suspension employed a traditional leaf spring design. This configuration provided a comfortable ride, even when carrying heavy loads. Braking duties were handled by ventilated discs on all four wheels, providing adequate stopping power. An Anti-lock Braking System (ABS) was standard. The robust frame and heavy-duty components ensured the truck could withstand the stresses of demanding work applications. Ride height provided good ground clearance for off-road use.
Market Reception & Comparison
The 2500HD with the 6.0L V8 and CNG capability was viewed as a niche offering within the Sierra lineup. Critics acknowledged its towing and hauling capabilities, but often pointed to the Duramax diesel engine as the superior choice for those prioritizing maximum performance and fuel efficiency. The CNG option was seen as a positive for environmentally conscious buyers and those with access to CNG fueling stations. However, the limited availability of CNG infrastructure hindered its widespread adoption. Compared to the diesel, the gasoline engine generally offered lower fuel economy, especially when towing. Reliability was generally good, but the CNG system added complexity and potential maintenance concerns.
Legacy
The GMC Sierra 2500HD IV (GMTK2XX) 6.0L V8 CNG variant, while not the most common configuration, remains a capable and durable work truck in the used car market. The Vortec LC8 engine is known for its longevity, and the Hydra-Matic transmission is generally reliable. The CNG system, if properly maintained, can provide cost savings and environmental benefits. However, potential buyers should be aware of the limited CNG infrastructure and the potential for CNG-specific maintenance issues. These trucks continue to be valued by those seeking a robust and affordable heavy-duty pickup for work or recreational purposes.
