BMW Details the Drivetrain of Its Production-Ready i8

Who would have thought that a day would come when we plug a BMW into a wall socket? That future is just about here, and the Bavarians are now willing to share how, exactly, its 2015 i8 hybrid sports car will work. As is becoming commonplace, power is derived from a gasoline engine—in this case, it's mid-mounted and works the rear rollers—driving one set of wheels, and electricity propelling their opposite numbers. This particular gasoline engine—dubbed B38, which we've sampled in a European-market 1-series hatchback—is a 1499-cc, 12-valve, three-cylinder constructed from aluminum (basically BMW's 3.0-liter inline-six cut in half) that makes use of the brand's Valvetronic variable valve timing and lift system. A balance shaft helps quell the vibrations of the triple in concert with a multi-stage damper housed within the six-speed automatic transmission. This mill is part of BMW's new engine family, variations of which will be found in the upcoming front-drive BMWs—previewed by the Concept Active Tourer—and the next-gen Mini. Turbocharged for the i8, the three-cylinder produces 231 horsepower and 236 lb-ft of torque. BMW points out that at 154 horsepower per liter, the little engine contains more concentrated oomph than any other lump the Bavarians produce. (For the sake of comparison, the 4.5-liter V-8 in a Ferrari 458 Italia rates at 125 horsepower per liter.) At the front end, motivation is provided by an electric motor with an integrated two-stage automatic transmission that is mounted near the front axle. It's a hybrid synchronous motor and, like every piece in the i8 driveline including the electronics and battery, it's been developed in-house. The electric motor makes 131 horsepower and 184 lb-ft of torque. That gives the i8 a total of 362 horses and 420 lb-ft of twist to push the i8's evenly distributed 3285 pounds of heft through the air—a drag coefficient of 0.26 further eases the strain on the powertrain. BMW says that all this results in a 0-to-60-mph time of less than 4.5 seconds and a top speed of 155 mph (limited to 75 mph when in electric-only mode). Electric-only range extends to 22 miles and the automaker claims mileage estimates of 95 mpg based on the European test cycle. Three drive modes are available—Comfort and Eco Pro can be selected when the car is in drive, and a Sport mode is a separate gear setting altogether—and they each alter the car's total range and characteristics. With a topped-up fuel tank and a full charge to the battery, the i8 is capable of traveling more than 310 miles in Comfort mode, and an additional 20 percent in Eco Pro. The Sport setting firms up suspension, increases energy regeneration, and allows drivers to operate the six-speed auto manually. First Drive: 2014 BMW i3 Instrumented Test: 2013 BMW ActiveHybrid 3 Instrumented Test: 2012 BMW ActiveHybrid 5 To give you a sense of the hybrid's size, it's seven-and-a-half inches longer, two-and-a-half inches wider, and a little more than two inches taller than the brand-new Corvette. Down the center of the i8 resides the lithium-ion battery in an aluminum housing.  The liquid-cooled pack can be fully recharged in three-and-a-half hours on 120 volts or an hour and a half on a 220-volt charger. The battery also can be recharged by the electric motor during overrun, by regen braking, or via the gasoline engine's starter-generator. The 2015 BMW i8 will make its production-ready debut at the Frankfurt auto show this September. We're hearing that the sport hybrid will feature prominently on showroom floors soon after the littler, less-athletic i3 does this spring. But even as we get used to the concept of the i8, will we ever get used to the question, "Honey, did you remember to plug in the BMW?" from Car and Driver Blog http://blog.caranddriver.com

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