No, this is not a concept vehicle. Rather, it is the efWING railcar truck with a leaf spring arrangement engineered with a carbon fiber reinforced plastic that was developed by Toho Tenax (tohotenax.com), part of the Teijin Groupâs carbon fiber and composites business, for Kawasaki Heavy Industries, which makes railcars. Ordinarily, railcar trucks use steel side frames and independent coil springs. In the efWING approach, there is a weight reduction of approximately 1,980 lb. per railcar, which results in fuel efficiency for and reduced emissions from the locomotive. While Kawasaki has been using this leaf spring for a few years, the two companies are now working toward developing a totally integrated systemâfrom the carbon fiber yarn all the way to the finished leaf springsâso that they will be able to mass-produce the components.