NSU Ro 80
NSU Ro 80 NSU Production=1967–1977
Full-size car Front Engine, Front Wheel Drive 4-door sedan Designed by Claus Luthe Engine=2x497.5cc;two-rotor Wankel engine, 115 hp (DIN) wheelbase=112.6 inch length=188.2 inch width=69.3 inch height=55.5 inch weight=2759-2848 lbs
When the milestone NSU Ro80 emerged in 1967, pundits confidently announced that every car would have a Wankel rotary engine by the 1980s. In this car, the rotary engine seemed to come of age, having first appeared in the tiny NSU Spyder sports car in 1963. Manufacturers clamoured to buy the license to build this light, compact and powerful new design, which had been developed by Dr Felix Wankel over many years, and had only three moving parts. It dispensed with pistons in favour of triangular rotors in epi-trochoidal housings - usually two, although you could have as many as you liked, in theory - and the engine got smoother, quieter and more powerful the faster the rotors turned. It was also remarkably compact, and was only two-thirds the weight of a pistoned power unit of equivalent capacity.
It took engineers some time to agree on how to measure the capacity of a rotary engine: on the basis of air consumption, the twin rotors of the Ro80 equated to less than 1000cc, which made its 115 bhp output remarkable. However, as the output shafts rotated three times as fast as the rotors, there were two strokes per drive shaft revolution, so most rated the Ro80 at about two litres.
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 (86 kW), 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 could 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). 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 the damage to the car's reputation and NSU's financial situation were irreparable. NSU was acquired by Audi (of the Volkswagen group) in 1969.
Other technological features of the Ro 80 aside from the powertrain were the four wheel disc brakes, which even now generally only feature on expensive sports or luxury sedans. 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 rack and pinion steering was used, again foreshadowing modern designs.
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 (practically unequaled for the era, although average for modern cars). This allowed for a top speed of 112 mph (179.2 km/h).
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.