General Motors has approved Impco Automotive’s bi-fuel compressed natural gas (CNG) fuel systems for shipment in the 2014 Chevrolet Silverado 2500HD and GMC Sierra 2500HD crew cab models.

Impco also obtained certification from the California Air Resources Board (CARB) and Environmental Protective Agency (EPA) for its system.

As an extension of GM’s manufacturing process, Impco installs the single-tank bi-fuel CNG system using GM’s OEM processes and standards. The entire gaseous fuel system adheres to GM’s strict quality, durability, and safety testing requirements to ensure a superior product, Impco said. Once the fuel system is in place, GM delivers these trucks to a dealer or to an up fitter for customer-ordered modifications.