NSU Ro 80

The NSU Ro 80 was a technologically advanced large sedan-type automobile produced by the German firm of NSU from 1967 until 1977. Most notable was the powertrain; a 113 bhp (84 kW; 115 PS), 995 cc twin-rotor Wankel engine driving the front wheels through a semi-automatic transmission employing an innovative vacuum system. It was voted Car of the Year for 1968 by European motoring writers.

Unfortunately for NSU, the car developed an early reputation for unreliability, from which it would never escape. The Ro80 engine in particular suffered from construction faults, among many other problems, and some early cars required a rebuilt engine before 30,000 miles (50,000 km), with problems visible as early as 15,000 miles (24,000 kilometres). The three-piece rotor tip seals were made out of the same material. The design fault caused the center section to have higher abrasion at cold starts than the corner pieces and the tip seals could push together, allowing the gas to blow past. With a changed tip seal design this was temporarily solved and with a tip seal center piece made of Ferrotic, the problem was entirely resolved.^[1][2] 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) since 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, particularly thanks to Mazda's perseverance with rotary design, the tip seal problem has been all but eradicated.
Other technological features of the Ro80, aside from the powertrain, were the four wheel ATE Dunlop disc brakes, which for some time were generally only featured on expensive sports or luxury saloon cars. The front brakes were mounted inboard, reducing the unsprung weight. The suspension was independent on all four wheels, with MacPherson struts at the front and semi-trailing arm suspension at the rear, both of which are space-saving designs commonly used today. Power assisted ZF rack and pinion steering was used, again foreshadowing more recent designs.
The car featured an automatic clutch which was commonly described as a three-speed semi-automatic gearbox: there was no clutch pedal, but instead, on top of the gearknob, an electric switch that operated a vacuum system which disengaged the clutch. The gear lever itself then could be moved through a standard 'H pattern' gate.
Interior trim combined cloth covered seats with PVC headlining and a carpeted floor.^[3]
The styling, by Claus Luthe who was head of design at NSU and later BMW, was considered very modern at the time and still holds up well; the Ro 80 has been part of many gallery exhibits of modern industrial design. The large glass area foreshadowed 1970s designs such as Citroën's. The shape was also slippery, with a drag coefficient of 0.355 (very good for the era, although average for modern cars). This allowed for a top speed of 112 mph (180 km/h). Indeed, comparisons have been drawn between the design of the Ro80 and the superbly aerodynamic 1982 Audi 100 - the shape is very, very similar.

Series production started in October 1967: the last examples came off the production line in April 1977. There were 37,204 vehicles produced during the ten year production run.