Forget lithium for a moment. The metal on the periodic table that could have the most impact on fuel consumption in cars and trucks over the next few years might be the same stuff used to make heat sinks and soda cans.
Car manufacturers have employed aluminum for more than a decade to take some of the heft out of engine blocks, wheels, car doors and trunk lids. Approximately 30 percent of car hoods are fashioned out of aluminum. The average U.S. car has 340 pounds of the stuff inside.
But now car manufacturers are experimenting with ways to employ the metal more extensively. Audi and Jaguar already produce high-end models with bodies made from two-thirds aluminum and one-third steel, says Randall Scheps, director of ground transportation and consumer electronics at Alcoa.
By 2015 or 2016, we might see the first wave of minivans and sedans with mostly aluminum frames. Long-haul truck manufacturers, meanwhile, are examining ways to employ aluminum for their frames. In the meantime, aluminum will become more prevalent in car doors.
“The level of interest has taken a step-function increase in the last 18 months,” he said. “We will move from niche, low-volume [manufacturing] into higher volumes.”
The shift largely comes about because of the more stringent fuel economy standards being imposed worldwide. The Obama administration and several car makers recently unfurled a new standard that will raise the average fuel efficiency of new cars and light trucks to 54.5 miles per gallon by 2025. Car makers currently hit an average of around 28.3 miles per gallon.
Similar regulations will require truck makers to increase mileage and reduce greenhouse gas emissions by 20 percent by 2018.
Aluminum’s popularity in part lies in its inherent properties. Aluminum weighs 40 percent less than steel and a lighter car goes farther on a gallon of gas than a heavier one. In essence, weight is the third fuel.
Gas mileage can be increased by 6 percent to 7 percent by reducing the overall weight of a car by 10 percent, Scheps said. A large 3,500-pound car mostly made from steel could shed, hypothetically, close to 400 pounds.
But the real driver turns out to revolve around technology and economics. Improving the efficiency of engines and power trains remains a challenge that can take several years and hundreds of millions of dollars in R&D.
Ford’s EcoBoost engine, a gas engine with diesel engine-like characteristics that can increase mileage by 10 percent to 15 percent, took several years to develop. And some high-tech engines, like the HCCI engines touted by Toyota and General Motors in the early part of the 2000s, can get stuck in an unending eddy of testing cycles.
Aluminum we understand. “The material is more expensive [than steel] and always will be,” Scheps admits. High strength steel might cost 50 to 60 cents a pound. Aluminum sells in the $2 per pound range. Still, since car makers largely have figured out how to work with it, the risks are greatly reduced.
“It is not so much that aluminum has become cheaper -- other fuel-saving technologies have become more expensive,” he said.
The cost delta, meanwhile, is also ameliorated by aluminum’s light weight. Because the same component will weigh 40 percent less, manufacturers need forty percent fewer tons to produce, roughly, the same amount of parts. Safety and dent-durability are comparable for aluminum and steel.
Aluminum typically is more difficult to spot weld than steel, so Alcoa, among others, has been dedicating more research to discovering new methods of joining sheets of metal together. Research is also underway on better adhesives and coatings.
Some of the new alloys may come from aerospace. Cars won’t need the same level of purity, so these alloys may be cheaper. While EVs and hybrids could benefit from less weight, aluminum bodies will likely appear first with heavier cars and trickle down.
Interestingly, more aluminum could allow car manufacturers to introduce more energy-efficient engines. Taking weight out of an economy car could, conceivably, also let a manufacturer substitute a four-cylinder engine with a three-cylinder engine without compromising performance. A four-cylinder aluminum car could exhibit the same performance as a six-cylinder steel one. Consumers wouldn’t have to buy “compromised” cars to get better mileage.
Lighter weight could also lead to changes in suspension and other components.
Other metals and even composites are being studied, but with its existing track record, you could argue that aluminum has the inside lane.