2015-2016 GMC Sierra 3500HD IV (GMTK2XX) Regular Cab Long Box 6.0 V8 (301 Hp) 4WD Automatic CNG

The GMC Sierra 3500HD IV, produced between 2015 and 2016, represented the fourth generation of GMC’s heavy-duty pickup truck line (GMTK2XX platform). This particular variant, a Regular Cab Long Box configuration powered by a 6.0-liter V8 engine producing 301 horsepower, and equipped with a 4WD system and an automatic transmission, was designed for customers needing substantial towing and hauling capacity, with the added flexibility of Compressed Natural Gas (CNG) capability. It occupied a mid-range position within the 3500HD lineup, offering a balance between capability and cost, appealing to commercial users and individuals requiring a robust work truck.

Technical Specifications

INTRODUCTION

The 2015-2016 GMC Sierra 3500HD with the 6.0L V8, 4WD, and automatic transmission, and CNG capability, was a workhorse designed for demanding tasks. Built on the GMTK2XX platform, it shared its underpinnings with the Chevrolet Silverado 3500HD. This generation represented a significant step forward in heavy-duty truck design, focusing on increased capability, improved refinement, and enhanced technology. The Regular Cab Long Box configuration prioritized cargo space and towing capacity over passenger comfort, making it a popular choice for commercial applications and owners who frequently haul heavy loads. The addition of CNG compatibility offered fleet operators and environmentally conscious buyers an alternative fuel option.

Powertrain & Engine Architecture

At the heart of this Sierra 3500HD lay the Vortec LC8 6.0-liter V8 engine. This engine, a staple of GM’s heavy-duty truck lineup for years, is a naturally aspirated, overhead valve (OHV) design featuring variable valve timing (VVT). The LC8 utilized multi-port fuel injection to deliver fuel to the cylinders. The engine produced 301 horsepower at 5000 rpm and 452 Nm (333.38 lb-ft) of torque at 4200 rpm. The engine’s robust construction and relatively simple design contributed to its reputation for reliability. The Hydra-Matic 6L90 six-speed automatic transmission was the sole transmission option for this configuration. This transmission was known for its smooth shifting and durability, and its gear ratios were optimized for both towing and fuel efficiency. The 4WD system employed an electronically controlled transfer case, allowing the driver to switch between two-wheel drive and four-wheel drive modes as needed.

Driving Characteristics

The 6.0L V8 and 6L90 automatic combination delivered a capable, if not particularly sporty, driving experience. The engine provided ample torque for hauling heavy loads and navigating challenging terrain. While the horsepower figure was respectable, the truck’s substantial weight (over 6,000 lbs) meant acceleration was moderate. The automatic transmission shifted smoothly and efficiently, and the gear ratios were well-suited for towing. Compared to the available Duramax diesel engine, the 6.0L V8 offered less torque and lower fuel economy, but it was significantly less expensive to purchase and maintain. Compared to the 6.0L with a manual transmission, the automatic provided greater convenience, especially in stop-and-go traffic, but some drivers preferred the more direct feel and control of a manual gearbox.

Equipment & Trim Levels

The Sierra 3500HD Regular Cab Long Box with the 6.0L V8 typically came standard with basic work truck features. These included vinyl upholstery, a basic audio system, air conditioning, and power windows and locks. Optional extras included upgraded audio systems, power-adjustable seats, a navigation system, and various towing packages. The CNG conversion was typically an upfit performed by a third-party installer, adding a dedicated CNG fuel tank and fuel system components. The interior was functional and durable, prioritizing practicality over luxury. The dashboard layout was straightforward and easy to use, with large, clearly marked controls.

Chassis & Braking

The Sierra 3500HD’s chassis was designed for heavy-duty use. It featured a robust frame, a coil spring front suspension with a transverse stabilizer bar, and a rigid axle rear suspension with leaf springs. This suspension setup provided a comfortable ride, even when the truck was heavily loaded. Braking duties were handled by ventilated disc brakes at all four corners, with ABS (Anti-lock Braking System) standard. The rear brakes were slightly larger (360x34mm) than the front brakes (350x40mm) to accommodate the increased weight typically carried in the bed. The steering system utilized a cone worm with recirculation balls, providing a solid and predictable steering feel.

Market Reception & Comparison

Critics generally praised the Sierra 3500HD for its robust construction, ample towing capacity, and comfortable ride. The 6.0L V8 engine was considered a good option for buyers who didn’t require the extreme towing power of the Duramax diesel. However, its fuel economy was a common criticism, especially compared to the diesel. The CNG option was viewed favorably by fleet operators looking to reduce their fuel costs and emissions. Compared to the Silverado 3500HD, the Sierra offered a slightly more upscale interior and exterior styling. The Ford Super Duty and Ram 3500 were the Sierra’s primary competitors in the heavy-duty truck segment.

Legacy

The 2015-2016 GMC Sierra 3500HD with the 6.0L V8 and automatic transmission has proven to be a reliable and durable truck. The Vortec LC8 engine is known for its longevity, and the Hydra-Matic transmission is also generally considered to be robust. On the used car market, these trucks remain popular among buyers seeking a capable and affordable work truck. The CNG-equipped models are particularly sought after by fleet operators and environmentally conscious buyers. While newer heavy-duty trucks offer more advanced technology and features, the GMTK2XX Sierra 3500HD continues to represent a solid value for those needing a dependable and capable pickup truck.