Ram Truck has expanded its bi-fuel compressed natural gas (CNG) 2500 pickup models to include a regular cab and rear-wheel drive configuration, Ram announced at the NTEA Work Truck Show.

The new configurations of the Ram 2500 bi-fuel CNG truck will be available by the end of 2015. The vehicle is powered by a 5.7-liter HEMI V-8 equipped with CNG fuel tanks and a choice of eight- or 35-gallon gasoline fuel tanks.

Ram has modified the engine by redesigning the cylinder heads and adding CNG compatible valves and valve-seat materials to allow the burning of either fuel. Unique spark plugs improve combustion and durability, and a unique powertrain control module allows the HEMI to seamlessly operate on either of the two fuel sources, according to Ram.

The system functions automatically by running initially on CNG and shifting to gasoline when that fuel has been fully combusted. The CNG-only range is 301 miles, while the backup supply of gasoline extends the range to 966 miles. The CNG tanks produce a gasoline gallon equivalent of 18.2 gallons.

The bi-fuel CNG Ram 2500 truck is assembled at the company's Saltillo, Mexico, plant. The truck gets a 5-year, 100,000-mile powertrain limited warranty.