Chevrolet and GMC have expanded the availability of bi-fuel versions of the new 2015 Silverado 2500HD/3500HD and Sierra 2500/3500HD pickup trucks.

These models feature a compressed natural gas (CNG) option, which provides reduced CO2 emissions compared to the gasoline engine, while delivering full-size truck utility.

The CNG option is available on all 2015-MY Silverado 2500HD configurations and Silverado 3500HD models with single rear wheels, along with the 2500HD double cab and crew cab models, and with 2500HD regular cab and all 3500HD models. The bi-fuel CNG option is available on standard- or long-box models in both 2WD and 4WD.

The bi-fuel CNG Silverado/Sierra 2500/3500HD uses the 6.0L Vortec V-8 with factory-installed hardened exhaust valves and intake/exhaust valve seats engineered for gaseous fuel use. The Vortec 6.0L V-8 engine can seamlessly transition between CNG and gasoline.

The CNG fuel delivery and storage system is covered under GM's limited warranty and is serviceable by Chevrolet and GMC dealers. Plus, all major components have GM service part numbers for broad availability.

The gasoline engine produces 360 hp and 380 lb.-ft. of torque. While running on CNG, the engine produces 301 hp and 333 lb.-ft. of torque.

The Silverado has a separate tank and allows the driver to seamlessly switch fuels with the flip of a switch. Not all bi-fuel systems allow drivers to manually switch fuels. In addition, the fuel system automatically switches to gasoline when the CNG tank is empty. The combined 17 gasoline gallon equivalent (GGE) CNG tank and 36-gallon gasoline tank provide a range of more than 650 miles, according to General Motors. The CNG tank is located in the pickup bed, and is installed by a GM supplier. The gasoline fuel gauge also doubles as the CNG fuel gauge.

In the CNG system, all high-pressure fuel lines are located between the frame rails. There is a full 10-year corrosion validation. The bi-fuel CNG Silverado/Sierra has a comprehensive five-year/100,000-mile transferable powertrain limited warranty, which is not the case for all manufacturers.