1990 BMW Z1

The Z1 roadster has the unique retractable door and window which slide electrically into the body sills. The car can be driven with the doors in this position. It has a galvanized  steel frame and is covered with unique thermo plastic panels manufactured by GE Plastics. 
To improve aerodynamics the Z1 has a plastic under shield and a rear muffler shaped like an upside down wing. This directs air flow and produces the necessary down force. There are no splitters or spoilers as they are not necessary.