The NSU company of Neckarsulm, Germany, (the NSU name was a derivative of Neckarsulm) began manufacturing knitting machines in 1873, later going into bicycles and motorcycles. It produced its first car in 1905, a Belgium Pipe model built under licence. By 1906, NSU had developed its own design and would build a variety of models until 1931, when it ceased auto production to concentrate on motorcycles.
NSU returned to building cars in 1957 with a tiny sedan called the NSU Prinz, powered by a 598-cc aircooled, two-cylinder, rearmounted engine. The Prinz was a moderate success, and from it evolved a diminutive coupe called the NSU Sport Prinz. The open Spider version of the Sport Prinz arrived in 1963, and was a real automotive pioneer in that it was the world's first production car with a Wankel rotary engine.
The rotary was the brainchild of German engineer Felix Wankel, who was convinced there was a more efficient way to produce power than by reciprocating pistons. He envisaged one continuous rotary motion, and patented his rotary piston engine in 1934. He later joined NSU, where it was finally introduced to the world in 1958.
Instead of conventional round pistons sliding in cylinders, Wankel used a triangular-shaped rotor turning inside a casing approximately the shape of a fat figure eight. By travelling a concentric path, the voids in the faces of the triangle created chambers of expanding and contracting volume that achieved the four cycles, intake, compression, power and exhaust, of the Otto cycle engine. The rotor rotated the crankshaft.
With the experience gained with the world's first Wankel-engined car, NSU followed it with a larger and much more ambitious undertaking, the NSU Ro80. It was introduced as a 1968 model and is the one for which the company would be best remembered. It was powered by a 115-horsepower two-rotor version of the Wankel with the equivalent of 2.0 litres of displacement.
The Ro80 was an intermediate-sized sedan with a relatively long 2,857-millimetre wheelbase. The sloping nose and wedgeshaped body were developed in the Stuttgart Polytechnic Institute's wind tunnel and had a coefficient of aerodynamic drag of .355, an exceptional figure at a time when air resistance was receiving little attention.
The windshield curved side to side and top to bottom, and the large side windows and thin pillars provided superb visibility. The Ro80's modern design could be considered at least a decade ahead of those of established manufacturers, no mean feat for a relatively small company.
Under its shapely skin were such advanced technologies as four-wheel independent suspension via struts and coil springs, four-wheel disc brakes and power rack-and-pinion steering. Power went to the front wheels through a three-speed, semi-automatic transmission.
But the real technical highlight was the Ro80's Wankel engine. It was smooth, quiet and vibrationless with performance that was good, if not outstanding. The zero-to-96 km/h acceleration time for the 1,211-kilogram sedan was in the 13-second range, with a top speed of about 177 km/h.
Unfortunately, the Ro80's rotary engine proved to be its Achilles heel. It soon developed problems, usually failure of the rotor tip seals. These seals, equivalent to piston rings, were critical engine components.
Although NSU had more rotary engine experience than anyone (others were experimenting with it) their limited resources didn't allow proper development.
The Ro80 was a bold and innovative step for a relatively small manufacturer, but economic pressures had unfortunately forced it to market too early.
In spite of NSU's attempt to defend its product by generously honouring warranties, further adding to their financial woes, the Ro80 developed a reputation for unreliability. The failing company was rescued in 1969 when it was bought by Volkswagen, who folded it in with its other recent acquisition, Audi.
Constant development and improvements in the Wankel engine gradually increased its reliability and, surprisingly, the Ro80 would be built for 10 years. When it was discontinued in the spring of 1977, total production had reached 47,400.
The NSU Ro80 was an advanced and daring design that was ahead of its time. Once its engine problems surfaced, however, its reputation was damaged to the point where it could never fully recover.
Japan's Mazda, another Wankel pioneer, was almost dealt the same fatal blow.
Mazda was building the engine under licence and fitting it to their cars, but when problems arose in the 1970s they had to fall back on the reciprocating piston engines for survival. In spite of this, their engineering genius Kenichi Yamamoto persisted and developed the rotary into a reliable engine that Mazda marketed in the popular RX-7 and RX-8 sports car.
Although the NSU Ro80 was a bold and progressive design from a small company, it was marred by early engine problems from which it could not recover.
