by :  GM plans to enter into direct competition with the likes of Fisker Automotive and Tesla Motors in the luxury green car market. How so? Not via the Chevy Volt, but rather instead through an announcement today it will, through its Cadillac brand, be developing a luxury coupe featuring extended-range electric technology called the Cadillac ELR.

The Cadillac ELR, according to the Detroit Free Press, will be “based on the same extended-range electric powertrain as the Chevrolet Volt.” This system, said the automaker, is “made up of a T-shaped lithium-ion battery, an electric drive unit, and a four-cylinder engine-generator. It will use electricity as its primary power source to drive the car and, “when the battery’s energy is low,” it will switch to a gasoline-powered electric generator to allow for greater range.

Cadillac ELR

The ELR is essentially the production version of Cadillac’s Converj concept vehicle, which was first unveiled back in 2009. If specifications hold true to the original concept, one would expect the car to have a range of almost 40 miles before the four-cylinder gasoline-engine kicks over to act as the generator. This would add what Cadillac says is extra “driving for hundreds of additional miles.”

Production is scheduled to begin in 2013 on the ELR at GM’s Detroit-Hamtramck Assembly plant, and its addition to that facility represents what GM says is a $35 million investment. It also increases total product investment to $561 million since December 2009 and is the first two-door car built at the plant since the 1999 Cadillac Eldorado.

The plant this Cadillac hybrid is being built at is the only U.S. automotive manufacturing plant that mass produces extended-range electric vehicles, according to GM. Not all of the vehicle will come from here though – for example, the lithium-ion battery will be built at GM’s Brownstown Battery Assembly plant in Brownstown, Mich.

GM noted the ELR will “advance the design theme of the Converj,” which from what learned of the vehicle when it was showcased in China in 2010, includes a conservative amount of grille openings that reduce drag at the vehicle’s front, and wheels shaped to push air outward for a smoother body side airflow.

The ELR will likely have low production numbers, and no specific pricing was mentioned.