Contrary to popular belief, automobiles have not become lighter during the last 15 years. In fact, they have become 30 percent heavier, due to numerous comfort, safety and entertainment devices that consumers have come to expect. For example, the Volkswagen Golf weighed 800 kilograms when it was introduced in 1974. Today’s version weighs more than 1,200 kilograms.

“By using plastic instead of metal, passenger cars will soon weigh up to 300 kilograms less than they do today,” says Roeland Polet, vice president of Ticona Technical Polymers (Kelsterbach, Germany). “Plastics help shed excess weight without compromising the comfort and safety features that are mainly responsible for the upward weight spiral.”

According to Polet, replacement of metal by plastic or other lightweight materials pays off if the total cost can be reduced by about 15 percent. “Ultimately, car manufacturers have to introduce cost-efficient overall solutions by reducing the number and scope of processing steps, while also reducing the weight of the finished component or system,” he explains.

Polet believes there are numerous opportunities to use plastic for under-the-hood applications. For instance, crankshaft flange seals made of polyphenylene sulfide are 32 percent lighter than their aluminum counterparts.

“In charge-air pipes for turbochargers, weight can be cut by 43 percent,” adds Polet. “Instead of 870 grams for an aluminum pipe, the same part produced from polyphenylene sulfide weighs only 500 grams.”