Wrightspeed is one of a growing number of companies that are trying to transform the market for commercial trucks that consume billions of gallons of fuel while spewing tons of carbon dioxide, nitrogen oxide and other pollutants. While more consumers are switching to electric cars like the Nissan Leaf, Chevy Volt or Tesla Model S, convincing commercial fleet owners to replace their diesel trucks won't be easy. When Wright left Tesla to start Wrightspeed, he planned to make high-performance electric sports cars, but he struggled to raise money from investors because the market wasn't big enough. [...] Wright switched gears and set his sights on the roughly 2.2 million commercial trucks in the U.S.