The tzero is a handmade electric sports car designed and built in very limited numbers by the U.S. company AC Propulsion in the early 2000s. It was the direct predecessor of the Tesla line of electric cars. The tzero was based on the Piontek Sportech kit car, which consists of a fiberglass body built over a reinforced steel space frame with double wishbone independent suspension and rack and pinion steering. AC Propulsion added the AC-150 drivetrain, a single-speed electric system with an overall gear ratio of 9:1.