Wednesday, August 3rd, 2011

The P-Word: Guess Which Material Shines in New BMW Electric & Hybrid Cars?

Two new BMWs—a fully electric city car and a four-seat, hybrid sports car—unveiled in Frankfurt, Germany on July 29, 2011 are more than radically cool vehicles. They also mark another step forward for reinforced plastic composites in the automotive sector.

Body panels of BMW’s new i8 hybrid sports car (left) and i3 fully electric city car are carbon-fiber-reinforced plastic, a first for the German carmaker.

The BMW i3 city car and the BMW i8 hybrid sports sedan each have a lightweight aluminum chassis and a “reinforced carbon-fiber body” that the company says compensates for the weight of the batteries. I put those words in quotes because the press material distributed for the launch uses carbon, carbon fiber, and CFRP to describe the bodywork, seemingly saying the structure is carbon. Is it that they don’t want to say what the carbon fibers are reinforcing,  or what is holding them together in those body panels?

The “P” in CFRP stands for plastic, which I finally found deep in the ample press material, where CFRP is explained as carbon-fiber-reinforced plastic. The P-word might be used again, I don’t know, but there’s no way to hide the actual CFRP—all the body panels are made of it, and they look good—really good. And if BMW’s engineers are betting on them to perform, the odds are extremely good that they will.

Other carmakers agree.

Porsche and performance electric carmaker Tesla are working with composites, and Land Rover’s new Evoque uses plastic composites for lightweighting. Jaguar is said to be developing a car expected to be one of the fastest in the world, and the C-X75 will also be fuel-efficient thanks to carbon-composite construction and a hybrid power plant, among other things.

BMW i8 sports sedan uses plastics and natural materials

BMW uses natural materials in the new i8, but the interior shows the designers also are using plastics—strikingly.

The new BMW i8's doors could be plastic

The BMW i8’s transparent, wing-type doors could be quite heavy in glass, but shaped as they are, they well might be plastic. BMW wasn’t saying at the intro.


Speaking of power plants, hats off to a dedicated engineer who may have reached his goal of making a practical composite engine block. Florida-based Matti Holtzberg has made a dozen versions of a composite engine block using a six-piece mold with a removable core for the oil passages. He followed the design of Ford’s 2-liter Duratec engine block but his composite version is 20 pounds lighter, in an industry happy to shed an ounce or a few grams. Car and Driver has more details, including a chronology of Holtzberg’s development of composite engine components that starts in 1969 in Hackensack, NJ. And let’s hear it for engineers who don’t give up on plastics.

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