BMW Z1
Before roadsters like the Z3, Z4, and the limited Z8, BMW introduced a strange-looking but very interesting Z1. In 1989, there was nothing similar on the market. The Z1 was a sleek roadster with unique styling, plastic body panels, and unusual sliding doors, which disappeared in rocker panels when opened. Technically, BMW Z1 could drive with the doors down (via Auto Express).
BMW built the Z1 on a special chassis that featured a new rear suspension setup. The power came from a well-known 2.5-liter six-cylinder engine with 168 hp that produced decent performance. The other interesting feature was plastic body panels directly onto the chassis. Owners could buy different color panels and attach them to the car at will. Essentially, you could change your car’s paint just by adding different colored doors, fenders, trunks, or hoods. In production until 1991, BMW made 8000 Z1 roadsters. The factory never tried to homologate Z1 for the US market, possibly because of unusual doors. They realized that the NHTSA would never approve this feature for safety reasons.