Toss everything you thought you knew about hybrid-electric vehicles out the window. Porsche has just green-lighted production of a car that will shake preconceptions about hybrids to their roots.

The Porsche 918 Spyder hybrid supercar, first shown as a concept at this spring's Geneva Motor Show, got official approval as a production model today from the company's board of directors.

And what a model. Just consider the specs: a 500-horsepower, 3.6-liter V-8 engine with a 9200-rpm redline, 0-to-62-mph acceleration of 3.2 seconds, and top speed of 198 miles per hour. Oh, and did we mention it gets 78 miles per gallon on the European cycle?

(As usual, please take all fuel efficiency numbers for plug-in hybrid vehicles with a very large grain of salt.)

The astounding fuel efficiency comes courtesy of an E-Drive mode that lets the 918 Spyder drive up to 16 miles on pure electric power, though [ahem] not at 198 mph.

All four wheels are powered, though the rears are driven through a seven-speed direct-shift gearbox by the V-8 with some extra torque from an electric motor. The front wheels are powered by a second electric motor; the pair adds 218 horsepower on top of the engine's 500.

Three additional modes--Hybrid, Sport Hybrid, and Race Hybrid--let the driver tune power delivery to ramp up both performance and speed. The Race Hybrid mode lets the driver simply push a button to add electric boost for overtaking.

Given the rapturous reception for the 918 Spyder Concept at Geneva, Porsche was faced with the question of production. It put a 1,000-buyer threshold on the decision, and in late April said the total was already at 900 or more.

The car will be designed and engineered in Weissach, Germany, and assembled in Porsche's factory in Zuffenhausen. First production models aren't expected for at least two years, which would make the car a 2013 or more likely 2014 model.

The 918 Spyder lets Porsche buff up its green credentials, but it also anticipates the arrival of zero-emission zones in the centers of some European cities.  The 16-mile electric range should be enough to get its owners in and out again, after which they can unleash the V-8.

This is not, by the way, the Porsche 911 GT3 R Hybrid race car, which uses a different, flywheel-based Kinetic Energy Recover System based on technology developed for Formula 1.

That car will debut for its first appearance in U.S. competition in the American Le Mans Series race to be held at the Road Atlanta racetrack on October 3.

The 911 GT3 R Hybrid race car and the 918 Spyder will be Porsche's halo cars as the company rolls out hybrid versions of two production models. The all-new 2011 Porsche Cayenne S Hybrid sport-utility vehicle is joined by a 2012 Porsche Panamera S Hybrid sedan as well.

[Porsche via Motor Authority]