The GMC Sierra 2500HD IV (GMTK2XX) Regular Cab Long Box with the 6.0L V8 engine and automatic transmission, produced from 2015 to 2016, represented a work-focused iteration of GMC’s heavy-duty pickup truck lineup. This configuration, notable for its optional Compressed Natural Gas (CNG) capability, occupied a middle ground within the 2500HD range, offering a balance between capability, fuel efficiency (particularly with CNG), and cost. It was positioned below the more powerful diesel options and above the base gasoline engine offerings, targeting commercial users and individuals needing substantial towing and hauling capacity without the premium price of a diesel.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD IV (GMTK2XX) Regular 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 | 2 |
| Doors | 2 |
| Fuel Type | Petrol / CNG |
| Weight-to-power ratio | 8.9 kg/Hp, 111.9 Hp/tonne |
| Weight-to-torque ratio | 6 kg/Nm, 168 Nm/tonne |
| 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 |
| Kerb Weight | 2690 kg, 5930.43 lbs. |
| Max. weight | 4536 kg, 10000.17 lbs. |
| Max load | 1846 kg, 4069.73 lbs. |
| Fuel tank capacity | 136 l, 35.93 US gal | 29.92 UK gal |
| CNG cylinder capacity | 67 kg |
| Permitted trailer load with brakes (12%) | 4355 kg, 9601.13 lbs. |
| Length | 5699 mm, 224.37 in. |
| Width including mirrors | 2035 mm, 80.12 in. |
| Height | 1976 mm, 77.8 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 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 Regular Cab Long Box, powered by the 6.0-liter Vortec LC8 V8 engine and paired with 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 step forward in terms of refinement, capability, and technology compared to its predecessors. The Regular Cab configuration, combined with the Long Box, catered to customers prioritizing maximum cargo space and utility over passenger comfort. The availability of a CNG conversion added a unique dimension, appealing to fleet operators and environmentally conscious buyers.
Powertrain & Engine Architecture
At the heart of this Sierra 2500HD lay the Vortec LC8 6.0-liter V8 engine. This engine, a staple of GM’s truck and SUV lineup for many years, featured a cast iron block and aluminum cylinder heads. It utilized a multi-port fuel injection system and an overhead valve (OHV) valvetrain with variable valve timing (VVT) to optimize performance and efficiency. The LC8 produced 301 horsepower at 5000 rpm and 360 lb-ft of torque at 4200 rpm. The six-speed Hydra-Matic automatic transmission, known for its durability and smooth shifting, was the sole transmission option for this configuration. The CNG conversion involved a dedicated CNG fuel system, supplementing or replacing the gasoline fuel system, allowing the truck to run on either fuel or a combination of both.
Driving Characteristics
The 6.0L V8 and automatic transmission combination delivered adequate, though not exceptional, performance for heavy-duty tasks. Acceleration was modest, but the engine provided sufficient low-end torque for towing and hauling. The automatic transmission’s gear ratios were optimized for work, prioritizing pulling power over quick acceleration. Compared to the available Duramax diesel engine, the 6.0L V8 offered significantly less torque and lower fuel economy, but it was also considerably less expensive to purchase and maintain. The ride quality, typical of a heavy-duty truck, was firm, even when unladen. The long wheelbase contributed to a stable ride, particularly when towing.
Equipment & Trim Levels
The Sierra 2500HD Regular Cab Long Box 6.0L Automatic typically came standard with basic work-truck features. This included vinyl upholstery, a basic audio system, air conditioning, and power windows and locks. Higher trim levels, such as SLE and SLT, added features like cloth or leather upholstery, upgraded audio systems, a rearview camera, and various convenience features. Optional extras included a trailer brake controller, a navigation system, and various appearance packages. The CNG-equipped models often featured specific badging and instrumentation to indicate their alternative fuel capability.
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 good balance of ride comfort and load-carrying capacity. Brakes consisted of ventilated discs at all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) was standard. The rear axle ratio varied depending on the specific configuration and intended use, influencing both towing capacity and fuel economy.
Market Reception & Comparison
The 6.0L V8/automatic combination in the Sierra 2500HD was generally well-received as a cost-effective option for buyers who didn’t require the ultimate towing and hauling capability of the diesel engine. Critics noted its adequate power and smooth shifting transmission, but also pointed out its lower fuel economy compared to the diesel. The CNG option was praised for its potential to reduce emissions and fuel costs, but its limited refueling infrastructure was a drawback. Compared to competitors like the Ford Super Duty and Ram 2500, the Sierra 2500HD offered a competitive combination of features, capability, and price.
Legacy
The Vortec LC8 6.0L V8 engine, while not as revered as the Duramax diesel, proved to be a reliable and durable powerplant. The six-speed Hydra-Matic automatic transmission also enjoyed a good reputation for longevity. Today, these trucks are readily available on the used market at relatively affordable prices. While they may not offer the fuel efficiency of newer trucks, they remain capable workhorses for those needing a robust and dependable heavy-duty pickup. The CNG-equipped models, while less common, represent a unique and potentially valuable option for buyers seeking an alternative fuel vehicle.
