As anyone who has ever rearranged furniture knows, the heavier an object, the more energy it takes to move it. The same principle applies to cars and trucks. The lighter a vehicle, the less energy it takes to accelerate, and the better its fuel economy.
However, weight is far from the only consideration when manufacturers design a car or truck. They also need to meet consumer expectations for safety, comfort, reliability, performance and cost. To meet these competing goals, the Energy Department is researching how to better use existing lightweight materials as well as working to develop new ones.
Today’s cars rely heavily on conventional iron and steel alloys, which make up 70 percent of most vehicles’ weight. Replacing established steel alloys with advanced, lightweight materials could potentially reduce the weight of a vehicle’s body and chassis by up to 50 percent. And this has a big impact on a vehicle’s efficiency — reducing a vehicle’s weight by 10 percent can improve the fuel economy by 6 to 8 percent.
Lightweight materials also allow cars — particularly electric vehicles — to carry advanced emission control systems, safety devices and electronic systems without increasing their weight. Increasing electric drive vehicles’ efficiency allows them to have longer all-electric ranges with smaller batteries — reducing cost, decreasing fuel use and improving convenience. If just one quarter of the light-duty vehicles in the U.S. used lightweight components and high-efficiency engines, we could save more than 5 billion gallons of fuel annually by 2030.
Currently, high-strength steel and aluminum are two of the lightweight materials closest to being used widely in everyday vehicles. Other materials, such as magnesium and carbon fiber composites, have the potential to reduce the weight of some components by 75 percent, though many technical challenges remain. They are more expensive, more complicated to join to other materials, more difficult to model and more challenging to recycle than conventional iron and steel alloys. To address these barriers, the Department is supporting the development of better and cheaper processes for manufacturing these materials. One of the Department’s most exciting lightweight materials projects is working with MOxST, an innovative metal production company.
In the early 2000s, MOxST was formed to scale up a promising technology into a system that fit on a tabletop and produced very small amounts of magnesium. Now, the Department is working with MOxST through a $6 million, competitive award matched by the company to develop a much larger prototype. While early versions of the system produced only grams of material, the new prototype is on track to produce thousands of pounds of clean, domestic magnesium by the end of the project. MOxST’s long-term goal is to produce magnesium that meets the economic, mechanical and physical requirements necessary for automakers to adopt the technology.
While the idea of making a vehicle lighter is simple, the process is far more complex. Fortunately, by discovering new ways to reduce vehicle weight, the Energy Department is helping manufacturers to meet the fuel economy and emissions standards for passenger vehicles built between model years 2017 and 2025.