Cadillac could be the first General Motors Co. brand to receive a plug-in hybrid electric vehicle powertrain that has been bouncing around at the auto maker since 2008.

The Cadillac XTS Platinum, an over-the-top luxury concept car hinting at a future fullsize sedan from the brand, debuts later today at the North American International Auto Show in Detroit.

The XTS Platinum concept features GM’s award-winning 3.6L V-6 engine with direct-injection technology, plus a PHEV propulsion system. The internal-combustion engine and PHEV technologies combine for a powertrain boasting 350 hp and 295 lb.-ft. (400 Nm) of torque.

GM does not provide fuel-economy estimates for the combination but says urban commuters would experience efficiency double that of a conventional hybrid. And the fully electric variable drive of the PHEV adds sportiness to the driving experience, the auto maker says.

GM recently has been trying to find a home for the PHEV system after it first introduced the technology at the 2007 North American International Auto Show in Detroit on a Saturn Vue cross/utility vehicle.

The CUV was scheduled for production in 2011, but a potential divestiture of Saturn, which ultimately failed and led to the death of the brand, sent the technology to Buick.

However, the Buick CUV slated to receive the technology also was killed last summer, after it scored poorly during a consumer clinic. GM has said it would find a home for the technology and keep it on a 2011 timetable.

GM says the XTS Platinum was designed from the inside-out, imagining the car as a sort of “personal headquarters, built for efficiency, luxury and connectivity.”

In addition to luxury appointments found inside other Platinum-series vehicles from Cadillac, such as hand-cut and sewn materials, the XTS uses organic light-emitting diodes (O-LEDs) in place of traditional gauges and screens.

Also, the instrument panel uses what designer call a “dead front.” A new approach that has been looked at in concept form by some other auto makers and suppliers, the instrument panels appear black until the car is turned on and then illuminates.

Additional interior features include premium leather seats with what GM calls a new style of automotive suede, as well as richly finished wood with lighting.

Overall, GM says the interior draws its inspiration from nature, “specifically the intricate layers of petals that combine to form an orchid.”

The exterior of the XTS Platinum further develops Cadillac’s Art & Science design language, GM says, but in a more progressive manner. For example, its sleek profile complements its advanced technology and provides the PHEV with its necessary aerodynamics.

GM showed a version of the concept to journalists and a select group of consumers last summer at its technical center in Warren, MI, just a few weeks after the company exited bankruptcy.

GM executives at the backgrounder declined to offer a timetable for the XTS, which would replace both the STS and discontinued DTS at the top of the brand’s passenger-car lineup.

As a production model, the new Cadillac fullsize sedan is expected to ride on the same Epsilon II platform underpinning the new-for-’10 Buick LaCrosse.

Recent media reports suggest GM has designated its Oshawa, ON, Canada, assembly plant as a production site for the car. However, GM officials have not confirmed the report.

jamend@wardsauto.com