Automakers Turn to Plastics for Lighter Vehicles, Increased Fuel Efficiency

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In their ongoing quest to squeeze more miles out of a gallon of fuel, auto manufacturers are increasingly turning to strong, lightweight plastics and plastic composites in an effort to reduce the weight of the vehicles they produce.

Less Weight = Less Fuel

It’s a matter of physics: The lighter the vehicle, the less power required to get it moving and the less energy needed to maintain a constant speed. Therefore, it burns up less fuel.

How much?

Reducing a vehicle’s weight can improve its fuel efficiency by as much as 6-8 percent for every 10 percent reduction in poundage, according to the U.S. Department of Energy. That means reducing a vehicle’s weight can have significant long-term benefits for consumers as well as for the environment.

Ford notes how the use of lightweight materials impacts all factors of a vehicle’s capability; the company stated: Few innovations provide a more wide-ranging performance and efficiency advantage than reducing weight. All factors of a vehicle’s capabilities—acceleration, handling, braking, safety, efficiency—can improve through the use of advanced, lighter materials.”

A big reason: Plastics and plastic composites have been demonstrated to be effective tools when it comes to “lightweighting” vehicles. Modern-day plastics account for roughly 50 percent of the volume of a typical vehicle, but only 10 percent of its weight.

Rise in Use of Plastics and Carbon Fiber

Long used in racecars because of their strength and light weight, carbon fiber-reinforced plastics (CFRP) now are making their way into use for production vehicles.

Ford acknowledges that CFRP construction played a key role in the making of its new GT supercar. Lessons learned from the use of lightweight plastic composites in the GT are expected to benefit its entire product line.

Chevy used CFRP hood and roof assemblies to shave seven pounds off the roof of its 2014 Corvette Stingray.

BMW turned to the use of CFRP in constructing the passenger compartment for its first electric vehicles. The savings in weight helped offset the weight of the high-voltage lithium-ion battery that powers the car.

Nissan’s Rogue crossover utility vehicle features the North American auto industry’s first all-thermoplastic, composite liftgate. The all-olefinic liftgate is fully recyclable, and its lighter weight is estimated to cut fuel use by 10 percent.

But the industry is just getting started here.

Plastics accounted for around 200 kilograms of a vehicle’s weight in 2014, and industry analyst IHS Chemical of Englewood, Colorado, expects that figure to rise to nearly 350 kg by the year 2020, an increase of 75 percent. By 2030, that figure is expected to nearly triple. IHS analysts see the use of carbon fiber in automotive manufacturing to jump to 9,800 tons by the year 2030, up from 3,400 tons in 2013.

Efforts to Reduce CO2 Emissions

The driving force behind the movement is the federal government mandate that all light-duty vehicles meet a Corporate Average Fuel Economy (CAFE) standard of 54.5 miles-per-gallon by the year 2025. For 2015, the standard is 33.8 mpg, so there is a ways to go.

The use of plastics and plastic composites are expected to help vehicles reach those standards.

Plastics are used in vehicles’ interiors in the dashboards, instrument panels, control switches, cup holders and more. And on the exterior, plastics are used in the design of body panels and bumpers, windows, headlamps and taillights, and fuel tanks and fuel lines. Plastics used in housings for electronics and braking systems help protect the features from corrosion and heat damage, which can extend their reliability and lifespan.

Making the Road a Safer Place

Not only do the plastics and plastic composites shave pounds off a vehicle, but they also play a key role in vehicle safety. Body panels and front and rear bumpers made from plastics absorb energy in the event of car crashes, helping to minimize impacts on the occupants inside.

Foam-filled roof supports help strengthen the roof structure in the event of rollovers. Molded plastic fuel tanks are of one-piece construction with no welded seams, which can help minimize splitting in the event of a crash. And those fuel tanks made of plastics won’t corrode, which can add to their life span.

Plastics and the Road Ahead

It is clear that over the last four decades, car designers have made good use in the application of plastics and plastic composites in the manufacturing of automotive vehicles, but the potential for more remains.

According to a report by the Plastics Division of the American Chemistry Council, the international consulting and research firm Ducker Worldwide estimates that another 400 pounds needs to be removed from the average car to reach the EPA-mandated equivalent 54.5 mpg standard by 2025.

Thus, the Council notes, “As the push to lightweight vehicles intensifies, projections indicate that plastics and polymer composites can and should play an even more substantial role in the automotive industry through 2025 and beyond.”