BMW's Secret Concept is a Diesel-Electric Plug-in Hybrid Coupe, Fast as an M3, Frugal as a Prius

We know that many of you are dying to learn about BMW's Vision EfficientDynamics sports car concept that's due to make its first public outing in Frankfurt so let's just say that here's the inside scoop. In a nutshell, it's a futuristic-looking, diesel-electric plug-in hybrid sports car with 2+2 seating, and no, it has nothing to do with the four-door coupe car seen in this set of spy shots that circulated around the net.

Power comes from a high-performance hybrid drivetrain that combines a small displacement three-cylinder diesel engine with two electric motors.

We were told that the total output of the diesel engine and the electric motors will be somewhere around 350 horsepower and that thanks to the lightweight construction and various high-tech features, the Vision EfficientDynamics concept will be as fast as BMW's own M3 sports car but at the same time, as fuel efficient and 'green' as a Toyota Prius hybird.

Another significant detail is that the prototype model can run on either the diesel engine, the electric motors or a combination of the two and from what we learned, the vehicle's battery pack can be partially charged through regenerative braking or fully charged from any standard outlet.

There's more to come this weekend so stay tuned on Auto Cars 2011.

*UPDATE: Official Video Added Below