Color us, oh, not very surprised at all.

General Motors confirmed yesterday that it would build the 2014 Cadillac ELR range-extended electric luxury coupe at its Detroit-Hamtramck plant, on the same line that builds the ELR's Chevrolet Volt sibling.

While this had long been discussed in the industry, GM made it official with an announcement that said preparations for ELR assembly "will soon be under way," and that production itself would begin late next year.

The announcement was made by Mark Reuss, president of GM North America.

The company's press release pegged the cost of adding the new model to Detroit-Hamtramck at $35 million, bringing GM's total investment in the plant since December 2009 to more than $560 million.

As well as the Volt, Detroit-Hamtramck builds the 2013 Chevrolet Malibu mid-size sedan, one of two sites to do so.

The plant is now being tooled up for production of the 2014 Chevrolet Impala full-size sedan as well.

GM's release also noted that the Cadillac ELR will be the first two-door car built at the plant since the 1999 Cadillac Eldorado.

The 2014 Cadillac ELR is the production version of the Cadillac Converj concept first shown at the 2009 Detroit Auto Show. It was approved for production in August 2011.

It is expected to use an upgraded version of the same Voltec range-extended electric powertrain as the Chevy Volt.

A lithium-ion battery provides 30 to 40 miles of all-electric range, after which a range-extending internal combustion engine switches on to turn a generator that provides electricity to the motor that drives the front wheels.

2011 Chevrolet Volt Production Line at Detroit-Hamtramck Assembly Plant

2011 Chevrolet Volt Production Line at Detroit-Hamtramck Assembly Plant

Unlike plug-in hybrids from Toyota, Ford, and others, the Volt runs entirely on electric power until its battery is depleted--its engine does not switch on for those first 30 to 40 miles.

The lithium-ion pack for the ELR will be assembled at GM's Brownstown, Michigan, battery plant, as the Volt's is now.

Today, Detroit-Hamtramck produces the Chevrolet Volt, the Opel/Vauxhall Ampera, and the Holden Volt--all minor variations on the same vehicle.

Collectively, those three vehicles are exported to 21 countries.

The ELR will be the first new body style for the Voltec powertrain since the December 2010 launch of the Volt itself.


Follow GreenCarReports on Facebook and Twitter.