With the design process completed, four street-ready cars were constructed. Each vehicle possessed 65 carbon fiber panels and cost $250,000 to build. Two of the four cars were specialized versions. One version was the flap version, which had hydraulics and flaps to detail the close-up shots where the vehicle propelled itself through the air. The other version was the jet version, in which an actual jet engine was mounted onto the vehicle, fueled by six propane tanks. Due to the poor visibility inside the vehicle by the driver, monitors were connected to cameras on the vehicle body. The professional drivers for the Tumblers practiced driving the vehicles for six months before they drove on the streets of Chicago for the film's scenes.