Updated

Cadillac has released a spy photo-style shot of its upcoming plug-in hybrid ELR undergoing testing on public roads just a week before its official unveiling at the North American International Auto Show.

The car is a luxury coupe version of the Chevrolet Volt of which few details have been revealed, but the basic shape of the vehicle can be seen under its black and white camouflage wrap.

With a stacked headlight cluster and a tapering greenhouse, the two-door strikes a more dramatic pose than the Volt, but shares that car’s blunt front end, blocked-off grille effect and aerodynamic chin spoiler. A partial rendering of the car’s profile was previously shown in December.

The front-wheel-drive ELR will use a version of the Volt’s plug-in hybrid drivetrain, but any updates to the system for the Cadillac have yet to be revealed. The $39,995 Volt has a maximum output of 149 hp and an all-electric range of 38 miles.

"Cadillac customers are going to enjoy the unique features ELR will bring to the market.  We’re going to change the way people think about luxury and electrification,” said Chris Thomason, ELR chief engineer in a statement released with the photo.

After a slow start in 2011, Volt sales tripled to 23,461 units last year, making it the best-selling plug-in car in the United States, but that was still far short of GM’s original goal of 45,000.

The relatively high price of the compact is often cited as the main reason for its low sales, compared to more conventional hybrids like the Toyota Prius, which outsold the Volt 6 to 1 in 2012. Many analysts have suggested that GM should have first introduced the high technology showcase as a Cadillac to help justify its low volume with a premium price.

We’ll soon fight out how right they were when the ELR goes on sale later this year as a 2014 model.