The GMC Sierra 2500HD IV (GMTK2XX) Crew Cab Long Box, specifically equipped with the 6.0-liter V8 engine producing 301 horsepower and paired with an automatic transmission, and capable of running on Compressed Natural Gas (CNG), was a heavy-duty pickup truck produced by General Motors for the 2015 and 2016 model years. This variant occupied a middle ground within the Sierra 2500HD lineup, offering a balance between capability, fuel efficiency (when utilizing CNG), and everyday usability. It was positioned below the more powerful diesel options, but above the base gasoline engine offerings, targeting buyers needing substantial towing and hauling capacity without the premium cost of diesel technology.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD IV (GMTK2XX) Crew Cab Long 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%) | 4082 kg / 8999.27 lbs. |
| Length | 6563 mm / 258.39 in. |
| Width including mirrors | 2045 mm / 80.51 in. |
| Height | 1981 mm / 77.99 in. |
| Wheelbase | 4258 mm / 167.64 in. |
| Front track | 1748 mm / 68.82 in. |
| Rear (Back) track | 1709 mm / 67.28 in. |
| Ride height (ground clearance) | 211 mm / 8.31 in. |
| Minimum turning circle (turning diameter) | 17.1 m / 56.1 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 Crew Cab Long Box with the 6.0L V8 and automatic transmission represented GMC’s offering in the increasingly competitive heavy-duty truck segment. Built on the GMTK2XX platform, this generation of Sierra 2500HD trucks aimed to provide a comfortable ride alongside impressive towing and payload capabilities. The addition of CNG capability on this particular variant was a response to growing interest in alternative fuels, offering fleet and individual buyers a potential cost savings and reduced emissions. This configuration was designed to appeal to customers who needed the strength of a 2500HD but didn’t necessarily require the higher cost and complexity of the Duramax diesel engine.
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD variant lies the Vortec LC8 6.0-liter V8 engine. This engine is a member of GM’s small-block V8 family, known for its durability 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 directly to each cylinder. The engine employs an overhead valve (OHV) valvetrain with variable valve timing (VVT) to optimize performance and efficiency across a wider range of engine speeds. The 6.0L V8 produces 301 horsepower at 5000 rpm and 452 Nm (333.38 lb-ft) of torque at 4200 rpm. The engine is mated to a six-speed Hydra-Matic automatic transmission, providing smooth and efficient gear changes. The CNG system is a bi-fuel setup, allowing the truck to run on either gasoline or compressed natural gas, or a combination of both.
Driving Characteristics
The 6.0L V8/automatic transmission combination in the Sierra 2500HD delivered adequate, though not exceptional, performance. Acceleration was sufficient for everyday driving and towing moderate loads. The automatic transmission was tuned for smooth shifts and optimized for towing, sometimes at the expense of aggressive acceleration. Compared to the 6.6L Duramax diesel, the 6.0L V8 offered less low-end torque, requiring the transmission to downshift more frequently when hauling heavy trailers or climbing steep grades. However, the gasoline engine was quieter and smoother than the diesel, and the CNG option provided a potential fuel cost advantage, depending on local fuel prices. The six-speed automatic transmission provided a reasonable spread of gear ratios, allowing the engine to stay within its optimal power band during various driving conditions.
Equipment & Trim Levels
The Sierra 2500HD Crew Cab Long Box 6.0L CNG typically came standard with features such as air conditioning, power windows and locks, a basic audio system, and a tilt steering wheel. The Crew Cab configuration offered spacious seating for five passengers. Higher trim levels, such as 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 spray-in bedliner, and various appearance packages. The CNG system itself was often an optional upgrade, adding dedicated fuel tanks and the necessary fuel system components.
Chassis & Braking
The Sierra 2500HD featured a robust chassis designed to handle heavy loads. 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 comfortable ride while maintaining excellent load-carrying capacity. The braking system consisted of ventilated disc brakes on all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) was standard. Due to the heavier weight of the CNG system, some models may have featured slightly upgraded suspension components to maintain ride quality and handling.
Market Reception & Comparison
The 6.0L V8/automatic Sierra 2500HD received generally positive reviews, particularly from buyers who prioritized affordability and simplicity over outright power. Critics noted that the engine provided sufficient performance for most tasks, but it lacked the towing prowess of the Duramax diesel. The CNG option was praised for its potential fuel cost savings and reduced emissions, but its limited refueling infrastructure was a drawback for some buyers. Compared to the diesel models, the 6.0L V8 offered lower maintenance costs and a simpler engine design. Fuel economy was comparable to other gasoline-powered heavy-duty trucks, and the CNG option could further improve fuel efficiency in certain applications.
Legacy
The 2015-2016 GMC Sierra 2500HD 6.0L V8 CNG variant remains a viable option in the used truck market. The Vortec LC8 engine is known for its reliability, and the Hydra-Matic transmission is generally durable. However, potential buyers should be aware of the potential maintenance requirements associated with the CNG system. These trucks offer a good balance of capability, comfort, and affordability, making them a popular choice for buyers who need a heavy-duty truck for work or personal use. The availability of the CNG option adds a unique appeal for those seeking an alternative fuel vehicle.
