NSU RO80

Unfortunately for NSU, the car developed an early reputation for unreliability, from which it would never escape. The Wankel engine in particular suffered from heavy wear on the rotor tip seals, among many other problems, and some early cars required a completely rebuilt engine before 30,000 miles (50,000 km), with problems visible as early as 15,000 miles (24,000 kilometres). The fact that the rotary engine design was inherently thirsty (typically 15-18 mpg) and a poor understanding of the Wankel engine by dealers and mechanics did not help this situation. By the 1970 model year, most of these problems were resolved, but a necessarily generous warranty policy and damage to the car's reputation had undermined NSU's financial situation irreparably. NSU was acquired by Audi (of the Volkswagen group) in 1969. Second hand Ro80s were virtually worthless in the 1970s due to the well-publicised engine problems, and a common "cure" for an ailing rotary engine was to simply swap it for a Ford V4 "Essex" engine (as found in Mk1 Transits) purely as it was one of the few engines compact enough to fit in the Ro80's engine bay. Thus in an ironic twist, one of the smoothest engines in the world was replaced by one of the roughest. The NSU's unpopularity caused by the above problems means that surviving examples are very rare, and are now considered highly-prized classic cars with values to match