Opel Turbo Manta, 1973. Initially 5 prototypes were built by British company Broadspeed for Opel for promotional and evaluation purposes. High fuel consumption and the cost of the conversion put Opel off marketing the car however Dealer Opel Team (D.O.T.), the British importer of Opel cars, went ahead with the project and another 28 cars were converted in 1974 based on the Manta Berlinetta model