When it comes to improving fuel economy, engines, powertrains, fuels and batteries seem to get all the attention.
But what about the car's traditional steel side panel or rooftop?
Using advanced lightweight materials on even the most basic car parts can improve overall fuel efficiency, too. According to the Department of Energy, reducing a vehicle's weight by 10 percent can improve fuel economy by 6 to 8 percent.
Steel has traditionally made up about 60 percent of a vehicle's total weight. But in order to meet consumer demands and increasingly stringent federal fuel economy standards, automakers are looking to alternatives, including advanced high-strength steel, aluminum, magnesium and carbon fiber.
Lightweight materials are a cost-effective way to boost fuel efficiency on conventional combustion engine vehicles and advanced automobiles like hybrids, electric vehicles and hydrogen fuel-cell vehicles.
"There are literally hundreds of different technologies that can be brought to bear to help improve fuel efficiency, but all of them begin with lightweighting," said Kevin Lowery, a spokesman with the aluminum company Alcoa Inc.
Luxury vehicles, like the Audi A8 sedan, have been using lightweight materials for years so that the car could take on a larger powertrain without adding weight and compromising on horsepower. But a new push for better fuel efficiency across the passenger vehicle fleet has more automakers using these materials across their lineup.
New federal fuel economy standards will require automakers to improve fleet efficiency to 54.5 mpg by 2025. Building upon that progress, Energy Secretary Steven Chu announced seven new research projects last month to accelerate the development of stronger and lighter automotive materials for cars and trucks.
"With strong, lightweight materials, we have an opportunity to dramatically increase vehicle fuel economy while helping America maintain its competitive edge in automotive design and manufacturing," he said following the announcement.
Aluminum in demand; steel gets stronger
Aluminum is the second-most common material in cars on the roads today after steel. But auto manufacturers have said they intend to double their use of aluminum by 2025, Lowrey said.
Ford Motor Co. announced this year it is looking to make the body of its popular F-150 light-duty truck largely out of aluminum, which would reduce the truck's weight by about 700 pounds and produce about 10 percent in fuel savings. On a hybrid vehicle, aluminum could improve the fuel economy by more than 13 percent compared to an equivalent car made of steel, according to Alcoa.
"There's not an OEM [original equipment manufacturer] anywhere in the world that isn't, as we speak, talking to an aluminum company," he said. "In years past, it wasn't that way."
Car components made of aluminum are anywhere between 10 and 40 percent lighter than conventional steel. But aluminum is about 35 percent more expensive than steel, and concerns linger that it might not be as durable.
So steel is still in the game. And new advanced high-strength steels can actually provide up to 35 percent in weight savings, according to the Steel Market Development Institute (SMDI).
The industry achieved these gains using a different chemistry to produce a stronger but more formable type of steel, dubbed "dual phase steel." Making these steels didn't add much any extra cost because it simply required changing the cooling rates on existing process lines, said Ronald Krupitzer, vice president of automotive applications for SMDI.
The industry can now make multiple types of steel that are two to three times stronger than they were a decade ago.
"If you make a component stronger, it can carry the same load as it did before, but you don't need as much steel to do it. You can make parts thinner, but they can absorb the same about of energy and hold the same load," Krupitzer said.