Polymer Composites: From the Racetrack to Main Street

Digital glowing outline of a car

The new BMWi car series is the most recent evidence that plastics and polymer composites, such as carbon fiber reinforced plastics, are bridging the material divide between high-performance race cars and passenger vehicles.

A recent USA Today article reports that BMW’s new i8 and i3 cars both rely on carbon fiber reinforced plastics (CFRP) for the large “passenger cell” of the vehicles. BMW has declared that CFRP is “an especially light and high-strength material that provides outstanding protection to vehicle passengers in the event of an emergency.”

CFRP components can absorb up to 12 times more energy than steel, which can improve safety in a collision. High-speed Formula 1 race cars, for example, are comprised of approximately 85 percent CFRP by volume but less than 25 percent by weight, resulting in reduced overall weight, improved performance, and lowered driver injuries.

This plastic composite not only contributes to safety—it also helps cars become more fuel-efficient by contributing to “light weighting.” CFRP is 50 percent lighter than conventional steel and 30 percent lighter than aluminum, which helps cars burn less fuel and results in fewer emissions. This will help save money at the gas pump and also help enable automakers to meet stringent CAFE fuel efficiency standards, requiring an average of nearly 55 miles per gallon for cars and light trucks by 2025.

“To achieve a leg up in the marketplace, auto makers are taking a hard look at the materials they are using,” noted Steve Russell, vice president of plastics at the American Chemistry Council in USA Today. “More and more they are turning to advances in plastics to bring their customers more fuel efficient vehicles.”

While CFRP parts have been used in various auto components for some time, making them has been an expensive and laborious process. But that’s changing quickly, according to the USA Today article:

One of the most impressive breakthroughs for the i8—and the sibling, 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 is slowly 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.

The move toward CFRP auto parts follows the trend by automakers to reduce component and vehicle weight, in large part by replacing heavier materials with lighter weight plastics and polymer composites. In fact, today’s cars are approximately 10 percent plastics by weight but 50 percent by volume. Plastics and polymer composites offer exceptional strength-to-weight ratios and design flexibility, which helps reduce fuel use and greenhouse gas emissions across wide range of vehicles.