Remember the BMW 1995 M3 Lightweight? It came with carbon-fiber trim around the gearshift and a carbon-fiber dash plaque. They were cool. The new M3/M4 and M6 cars from BMW also have some carbon fiber in them. Maybe a tad bit more than the old E36 Lightweight—like the entire roof, for example. And the driveshaft, rear spoiler, center console, bumper supports, and door panels.
BMW refers to the substance as carbon-fiber-reinforced plastic (CFRP). It has a particularly favorable strength-to-weight ratio and is therefore ideal for body components. For the same functionality, CFRP is around 30 percent lighter than aluminum and 50 percent lighter than steel. Used in the right places, this material reduces weight, lowers the vehicle’s center of gravity, and improves body strength. The new BMW i3 and BMW i8 models also make extensive use of CFRP.
BMW has been working on other applications for CFRP, especially in the area of rotating-mass components. One example is the aforementioned driveshaft on the M3/M4, which is produced as a single-piece component without a center bearing. It weighs 40 percent less than a steel driveshaft and the lower weight and lower rotating mass result in better performance.
BMW has released photos of some exciting CFRP projects: wheels and steering wheels, for example. On the horizon for consumer use are wheels made completely from CFRP and wheels that are CFRP/light alloy hybrids. These wheels, which are 25 to 35 percent lighter than normal alloy wheels, might be on the market as early as two years from now. The carbon-fiber-framed steering wheel looks stunning.
Going forward, BMW and Mini models will also benefit from CFRP in other ways. For example, production offcuts can be reprocessed into “secondary” (recycled-content) CFRP, which will result in reduced-weight components such as seat frames, instrument panel frames, and spare wheels.
BMW is absolutely committed to maximizing the use of CFRP. They are partners with the German company AGL in CFRP manufacturing plants in Moses Lake, Washington (that is powered with electricity from a hydroelectric plant, by the way), and Germany. Recently they announced they would be doubling CFRP production, split evenly between the two facilities.
It’s obvious that carbon fiber is not just for dash plaques anymore.—Scott Blazey
