[6] Bmw I8 2015 | [+] MANTIS TILLER

Power output of 362 horsepower and torque of 420 pound-feet is reasonable for a 3,300-pound sports coupe with a low drag coefficient of 0.26, but it's nowhere near the top of the power charts. But suppose you combine those specs with advanced carbon fiber construction, the ability to run electrically for 20 miles or so--and gas mileage that might reach 50 mpg or more otherwise?

That's the premise of the 2015 BMW i8 plug-in hybrid sports coupe, which was unveiled in production form this morning at the 2013 Frankfurt Auto Show. When it reaches dealer showrooms in the U.S. sometime next spring, the base price will be $135,925 including destination.

BMW's first-ever plug-in hybrid, the i8 is deemed a "revolutionary interpretation" of BMW's tradition of ultimate driving machines. Certainly the technology is advanced: The BMW i8's turbocharged 1.5 three-cylinder engine, mounted low and behind the passenger compartment, uses its 231 horsepower and 236 pound-feet of torque to drive the rear wheels via a six-speed automatic gearbox.

A liquid-cooled lithium-ion battery pack sits between the two passenger seats in the tunnel, and provides electricity to run the electric motor--rated at 96 kilowatts (131 horsepower) and 184 pound-feet of torque--that powers the front wheels. Range in electric mode is up to 22 miles, at up to 75 mph.

2015 BMW i8

Each of the two separate powertrains will run the i8, or they can be used together in Sport mode for maximum performance, with the electric motor providing short bursts of what BMW calls "boost" for extra acceleration. Such an arrangement is called a "through-the-road hybrid," and it's the same setup used for the limited-edition Porsche 918 Spyder plug-in hybrid sports car--which is much more expensive.

The body shell of the 2015 i8 coupe is built of carbon fiber-reinforced plastic (CFRP), both very light and very strong, sitting on an aluminum platform that absorbs crash energy and contains the battery pack, electric motor, and rear-mounted engine and transmission. BMW quotes the curb weight at just 3,285 pounds, and says the i8 has a center of gravity that's less than 18 inches above the ground and a drag coefficient of 0.26.

Among the notable design touches are doors that pivot upward, somewhat like wings; standard full LED headlights--with laser headlights, a world first, where they're legal to use--and alloy wheels fully 20 inches in diameter.

We'll have live photos from the BMW i8 introduction, and be sure to check out all our coverage from Germany this week on our Frankfurt Auto Show page.

____________________________________________

Follow Motor Authority on Facebook, Twitter, and Google+.