2015-2016 Chevrolet Silverado 3500 HD III (K2XX) Double Cab Long Box 6.0 V8 (301 Hp) Automatic CNG

The Chevrolet Silverado 3500 HD III (K2XX) Double Cab Long Box, 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 Chevrolet for the 2015 and 2016 model years. This variant occupied a significant position within the K2XX Silverado 3500 HD lineup, offering a balance between capability, fuel flexibility, and passenger space. It catered to buyers needing substantial towing and hauling capacity, but also desiring the convenience of a double cab configuration and the potential cost savings of CNG operation.

Technical Specifications

Introduction

The K2XX generation of the Chevrolet Silverado and GMC Sierra HD trucks debuted in 2015, representing a significant redesign focused on increased capability, refinement, and efficiency. The Silverado 3500 HD Double Cab Long Box with the 6.0L V8 and automatic transmission offered a compelling option for customers needing a robust work truck with the added benefit of CNG compatibility. This configuration was positioned as a mid-range offering, slotting between the base 6.0L gasoline models and the more expensive Duramax diesel variants. The Double Cab configuration provided increased rear-seat space compared to the standard cab, making it suitable for crews or families, while the long box offered ample cargo capacity.

Powertrain & Engine Architecture

At the heart of this Silverado 3500 HD variant lies the Vortec LC8 6.0-liter V8 engine. This engine is a member of Chevrolet’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 also incorporates Overhead Valve (OHV) valvetrain with Variable Valve Timing (VVT) to optimize performance and efficiency. The 6L90 six-speed automatic transmission, known as the Hydra-Matic, was the standard transmission for this engine. This transmission is electronically controlled and designed to handle the high torque output of the 6.0L V8. 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 301 horsepower and 333.38 lb-ft of torque provided by the 6.0L V8 and 6L90 automatic transmission delivered adequate performance for most heavy-duty tasks. While not as powerful as the Duramax diesel, the gasoline engine offered a more familiar driving experience and a lower initial cost. The 6L90 transmission provided smooth and relatively quick shifts, although it wasn’t as aggressively tuned for performance as some other automatic transmissions. The gear ratios were optimized for towing and hauling, prioritizing low-end torque over outright acceleration. Compared to the manual transmission equipped versions, the automatic offered greater convenience, especially in stop-and-go traffic. However, the manual transmission generally provided slightly better fuel economy and a more direct connection to the engine.

Equipment & Trim Levels

The Silverado 3500 HD Double Cab Long Box 6.0L CNG typically came standard with features such as air conditioning, power windows and locks, a basic audio system, and vinyl upholstery. Higher trim levels, such as the LT and LTZ, added features like leather upholstery, heated seats, a premium audio system, navigation, and advanced safety features. The CNG system itself was often an optional upgrade, adding a dedicated CNG fuel tank and fuel system components. Exterior features included standard halogen headlights, and available options like chrome bumpers and running boards.

Chassis & Braking

The Silverado 3500 HD featured a robust chassis designed to handle heavy loads. The front suspension utilized an independent torsion bar setup with double wishbone components, providing a comfortable ride and good handling. The rear suspension employed a traditional leaf spring design, offering excellent load-carrying capacity. Braking duties were handled by ventilated disc brakes on all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) was standard equipment. The truck’s heavy-duty construction and substantial weight contributed to its stability and towing capability.

Market Reception & Comparison

The Silverado 3500 HD 6.0L CNG variant received generally positive reviews, particularly from those seeking a cost-effective and environmentally conscious heavy-duty truck option. Critics praised its capability, comfortable ride, and the potential fuel savings offered by the CNG system. However, the 6.0L engine was often criticized for its lower power output compared to the Duramax diesel, and its fuel economy was not as competitive as some other gasoline-powered trucks. Compared to the 6.6L Duramax diesel, the 6.0L offered significantly less towing capacity and fuel efficiency, but at a lower purchase price. The 6.0L also required less expensive maintenance than the diesel.

Legacy

The Silverado 3500 HD III (K2XX) 6.0L V8 Automatic CNG powertrain has proven to be relatively reliable in the long term. The Vortec LC8 engine is known for its durability, and the 6L90 transmission is generally considered a robust unit. However, like any vehicle, regular maintenance is crucial to ensure longevity. On the used car market, these trucks represent a good value for buyers needing a capable and affordable heavy-duty pickup. The CNG compatibility adds a unique selling point, appealing to those seeking to reduce their fuel costs and environmental impact. While the diesel variants remain more popular, the 6.0L CNG Silverado 3500 HD continues to be a viable option for those prioritizing value and fuel flexibility.