The General Motors HX3 concept vehicle utilized technology which entered production in the early 21st century. Resembling the minivan of the future, the HX3 combined electric and gasoline engine power. Electric motors in the front wheels received power from a pack of 32 lead-acid batteries. When the level of the charge was low, a three-cylinder gasoline engine automatically fired up and recharged them, running at a constant speed. The aerodynamic body featured removable rear fender skirts and flush glass enclosing a living room-type interior capable of holding up to five full-size passengers and their luggage. A 120-inch wheelbase and a 184.5-inch length were not far from different from conventional minivans. Low-resistance Goodyear tires worked with the body styling to keep demands down on the HX3’s mechanics.