Chevy Volt, Cadillac ELR could get downsized three-cylinder range extender

Three may be the magic number for General Motors and its effort to cut both fuel use and weight in its next-generation extended-range plug-ins, both the new Chevrolet Volt and Cadillac ELR.

GM, along with its China-based vehicle-development partners, may build a three-cylinder gas-powered range extender for the two plug-ins, Edmunds says, citing industry sources it didn't identify. The engines would range from 1.0 to 1.2 liters and would replace the 84-horsepower, 1.4-liter four-cylinder engine that is used in the current Volt.

This new engine would help GM increase fuel economy and cut weight in its upcoming PHEVs, though no specifics on how much of an improvement would be possible have been disclosed. The engine would be swapped into the Volt in 2015 and into the ELR the following year.

Currently, the Volt is rated by the Environmental Protection Agency (EPA) to get 98 miles per gallon equivalent in electric mode and 37 miles per gallon combined in gas-powered mode.