Lightweighting vehicles is a big deal. The lighter the car, the less relative energy required to move it down the road. This thinking has been influencing car design and manufacturing for some time now as automakers strive to make models with higher fuel efficiency, but the momentum has increased because of the much higher mpg that will be required from automakers in the years ahead. Now, each and every part of a car is examined for lightweighting potential and new answers are emerging all the time.

Take the new ultra lightweight car door solution devised by ArcelorMittal, the world’s largest steel and mining company and supplier to many auto manufacturers. In a world where lightweight aluminum, plastics, and other materials vie for roles once exclusively played by steel, it’s no wonder that steel companies have a vested interest in illustrating how advanced steel can continue to dominate.

ArcelorMittal’s lightweight car door example demonstrates that using steels and technology currently available, a 27 percent weight and cost saving can be achieved without compromising safety and structural requirements. But it gets better. The company also points out that its global research and development team has identified that even greater door weight savings of up to 34 percent is achievable with new advanced high strength steels and technology that will emerge during the next few years.

How important is this? The current 27 percent weight reduction of a baseline C-segment door using high strength steels and ultra-high strength steels decreases weight from about 40 pounds to 29 pounds. Considering that automotive weight savings is typically measured in grams, this is a significant weight reduction for a single automotive application.

It’s a given that it will take more than just better powerplants to reach the 54.5 mpg federal fuel economy standard set for coming years. To this end, automakers are exploring every part of an automobile for ways to eke out greater efficiencies.

An interesting new exploration is taking place at General Motors, which is testing an industry-first thermal-forming process and proprietary corrosion resistance treatment for lightweight magnesium sheet metal. GM’s aim is to enable its suppliers to use the process and provide magnesium sheet in lieu of steel and aluminum that trims pounds from vehicle mass.

This is no small thing. Magnesium weighs 33 percent less than aluminum, 60 percent less than titanium, and 75 percent less than steel. Despite its advantages, there have been challenges and automakers have found it difficult to make strong and non-corroding magnesium sheet metal panels through traditional methods. GM’s has now overcome this with a new, patented process that heats the magnesium to 842 degrees F to allow molding it into precise, rigid shapes. GM has used this process to develop a production-ready magnesium rear deck lid inner panel that’s undergone rigorous testing without any issues.

The U.S. Automotive Materials Partnership estimates that 350 pounds of magnesium will replace 500 pounds of steel and 130 pounds of aluminum per vehicle by 2020, achieving a vehicle weight reduction of 15 percent. This weight savings would lead to a fuel savings of 9 to 12 percent.