1968 NSU Ro80
1968 NSU Ro80. Click image to enlarge

Story and photo by Bill Vance

The NSU company of Neckarsulm, Germany, (the NSU name was of derivative of Neckersulm) began manufacturing knitting machines in 1873, later going into bicycles and motorcycles. It produced its first car in 1905, a Belgiun Pipe model built under licence. By 1906 NSU had developed its own design, and went on to build a variety of models until it ceased auto production in 1931 to concentrate on motorcycles.

NSU returned to building cars in 1957 with its tiny NSU Prinz sedan. It had all-independent suspension and was powered by a 598-cc air-cooled, vertical, two-cylinder, rear-mounted engine.

The Prinz was a moderate success, and from it NSU developed a diminutive coupe called the Sport Prinz. This was the car, in the open Spider version which arrived in 1963, that would secure a firm place for NSU in automotive history. It departed from the long established reciprocating piston engine and became the world’s first car to be powered by a Wankel rotary engine.

The rotary was the brainchild of German engineer Felix Wankel who was convinced there was a more efficient way of producing power than by inertia-laden reciprocating pistons. He envisaged developing power in one continuous rotary motion, and patented his rotary piston engine in 1934. As an NSU engineer he was finally able to introduce it to the world in 1958.

Instead of conventional round pistons sliding in cylinders, Wankel used a triangular-shaped rotor turning inside a casing about the shape of a fat figure eight. By travelling a concentric path, the faces of the triangle created chambers of expanding and contracting volume which achieved the intake, compression, power and exhaust cycles of the Otto cycle engine. The rotor fed the power to the crankshaft in a continuous rotary motion.

While the NSU Spider was the world’s first Wankel-engined production car, the model that followed was a much more ambitious undertaking. It was the NSU Ro80 introduced as a 1968 model, and the one for which the company would be best remembered. The Ro80 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 mm (112.5 in.) wheelbase. The sloping nose and wedge-shaped body that was developed in the Stuttgart Polytechnic Institute’s wind tunnel yielded a coefficient of aerodynamic drag of .355. This was an exceptional figure in an era when air resistance was receiving little attention.

The windshield was 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 established manufacturers, no mean feat for a small auto manufacturer.

Under its shapely skin the Ro80 exhibited much advanced technology for the 1960s. The four wheels were independently suspended via struts and coil springs. Four-wheel disc brakes and power rack-and-pinion steering were fitted, and power went to the front wheels through a three-speed, semi-automatic transmission.

The real technical highlight, however, was the Ro80’s Wankel engine. Smooth, quiet and virtually vibrationless, its performance was good, though not outstanding. The zero to 96 km/h (60 mph) acceleration time for the 1,211 kg (2,770 lb) sedan was in the 13 second range, with a top speed of about 177 km/h (110 mph).

Unfortunately what should have been the Ro80’s tour de force – its rotary engine – proved to be its Achilles heel. It soon developed problems, usually failure of the rotor tip seals. These seals, equivalent to the piston rings in a conventional engine, were critical components.

Although NSU had more rotary engine experience than anyone (other manufacturers were experimenting with it) their limited resources didn’t allow them to develop it properly. The Ro80 was a bold and innovative step for a relatively small company, but economic pressures had forced them to bring it to market too early.

In spite of NSU’s attempt to defend its product by generously honouring warranties, which further added to their financial woes, the Ro80 developed a reputation for unreliability. The failing company was rescued in 1969 by Volkswagen, who purchased it and folded it in with Audi, their other recently acquired automaker.

Constant development and improvements in the Wankel engine gradually increased its reliability and, surprisingly, the Ro80 continued to be produced for 10 years. When the last one was built 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, it was damaged to the point where it could not fully recover.

The Wankel almost dealt the same fatal blow to Japan’s Mazda, who were building it under licence. They were forced to fall back on the reciprocating piston engines in the 1970s. But their engineering genius Kenichi Yamamoto persisted with the rotary, and developed it into a reliable engine which Mazda confidently marketed in their popular RX-7 sports car.

If NSU had had a Yamamoto, the story could well have been different. As it was, however, the Ro80’s advanced design was marred by early engine problems from which it never recovered.

Connect with Autos.ca