News Column

BMW i8 Rolls Through Tech, Energy Barriers

June 3, 2014

By Chris Woodyard, @chriswoodyard, USA TODAY

The new i8 from BMW  retails for more than $135,000 and will be available starting in September. (photo: BMW)
The new i8 from BMW retails for more than $135,000 and will be available starting in September. (photo: BMW)

In a crowded field of conventional sports cars, the BMW i8 is a high-tech wonder.

It offers all the performance you'd expect in a $135,700 sports car, but does it with a tiny, three-cylinder engine and fuel economy that's expected to shame a Toyota Prius hybrid.

The new BMW i8 plug-in hybrid, due in showrooms in September, is intended as a sports car for a new age, breaking through engineering and technological barriers.

While the i8 seems exotic now, the lessons learned in building it point the way to an energy-efficient future for mainstream cars. The technology combines power plants in new ways and uses plane-like lightweight construction with extensive use of aluminum and carbon fiber.

"The combination of incredible styling, performance and efficiency wrapped in carbon fiber-reinforced plastic is significant on many levels," says Ron Cogan, publisher of the Green Car Journal, which follows advanced-car developments. "It's a breakthrough."

The i8 shows production-ready answers for the high-wire act that the auto industry must perform as it faces tightening government fuel-economy and carbon-emission mandates.

On one hand, that's creating intense pressure to cut engine sizes and performance and sell smaller, lighter vehicles. On the other, it has to try to sell those cars to consumers who not only crave performance but also space in a vehicle and higher safety standards.

The i8 shows how one automaker has leaned on advances in technology to meet competing demands:

•Power. The i8's three-cylinder engine displaces only 1.5 liters, about the size of the 1.4-liter, four-cylinder turbocharged engine in the popular Chevrolet Cruze compact sedan. But while the Cruze engine generates 138 horsepower, the i8's engine has twin turbochargers and develops 231 horsepower.

That gas engine in the back of the car then is coupled to an electric motor in the front, good for another 131 horsepower, and a lithium-ion battery in between for low center of gravity and weight balance. The result is an all-wheel drive car with with a combined maximum power and torque of 362 hp. and 420 pounds feet of torque.

As a result, i8 can rocket from zero to more than 60 miles per hour in about 4.5 seconds, nearly the same as a Porsche Boxster.

•Gas savings. Because it's a plug-in hybrid, actual fuel economy will vary based on how far owners drive on electricity only when they have a full charge in the battery pack, which can be recharged in 1.5 hours. While the car doesn't have a government rating yet, BMW hope for an overall mileage rating in the 60- to 70-miles-per-gallon range. A Prius averages 50 mpg.

The i8 can drive up to 23 miles on electricity alone at speeds up to 75 mph -- and drivers can choose from five settings that balance performance vs. fuel conservation. In hybrid mode, the i8 can go 310 miles between fill-ups, BMW says.

•Aerodynamics. Designers turned the i8 into an aerodynamic wonder in a quest for extra battery range and also high-speed sports-car performance. But it looks like a beauty, not a science project. The car was given a teardrop shape that tapers wind passing from the bow to the stern.

•Materials.The i8's body and "passenger cell" is made of lightweight carbon fiber. One of the most impressive breakthroughs for the i8 -- and its sibling, the all-electric i3 sedan -- was to be able to produce the material, long used in race cars, at a cost and in a volume for production cars.

The i8's use of carbon fiber underscores how it's gradually becoming a mainstream material as makers find more efficient composites and ways to produce them. "Carbon fiber is really poised to take off," says Steve Russell, vice president for plastics for the American Chemistry Council.

BMW is so proud of its use of the material that it commissioned Louis Vuitton to make a set of matching luggage for the i8. Sounds like a throwback to the grand touring cars of the 1930s, but the bags aren't leather, they're carbon fiber.

BMW also had to make compromises. The i8 carries 440 pounds of battery and electric motor and tops out at 3,285 pounds, about 200 more pounds than the Cruze. The interior is limited, partly because of the space taken up by its powertrain components. The space under the rear hatch, just behind the gas engine, won't hold much more than a couple of laptop bags. BMW spokesman Manfred Poschenrieder says i8 should be looked upon as a 2-plus-2, with the back seats more for cargo than people.

But BMW doesn't sound particularly worried about finding buyers.

"Selling the car is going to be a walk in the park," says Henrik Wenders, head of product management for BMW's "i" division, its unit for alternative cars. He says none of i8's rivals offer "the driver so many different facets, different characteristics" -- the ability to save gas around town, to go on a long trip without range worries or to put it through its sports-car paces on a track.


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Source: Copyright 2014 USA TODAY


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