By on January 2, 2020

Today’s Rare Ride was a relative revolution at the time of its introduction. With smooth, aerodynamic styling and a rotary engine, NSU’s Ro 80 made big promises. Years later, one man decided he’d create the convertible that was missing from the Ro 80 lineup. Let’s check out this one-of-two NSU.

We’ve previously touched on the history of NSU in a four-part series on the Wankel-powered Spider from 1965. NSU continued its development of rotary power, and shortly after the Spider the company introduced the considerably more modern Ro 80. NSU was at the end of its independence around the time the new sedan debuted; two years later, the company merged with the Auto Union. And that organization subsequently merged with, and was crushed by, VW-Audi. The Ro 80 was then the first and last modern NSU sedan.

Introduced in 1967, the Ro 80 was marketed to wealthy customers as an executive sedan. Available in four-door format only, smooth styling covered a bevy of advanced technology. Ro 80 was front-wheel drive, powered by a 113-horsepower Wankel engine of 995 cc displacement. A single transmission greeted buyers: the ever-obscure semi-automatic. Three manual speeds with synchromesh were operated by an automatic clutch. That meant a traditional gear lever shifted by the driver, who touched a knob on the lever to activate the vacuum-operated clutch.

Steering was electrically assisted and used a ZF rack and pinion design. Other important advanced technology included four-wheel disc brakes mounted inboard at the front, and an all-independent suspension. Said suspension was modern for its time, utilizing a MacPherson layout at the front and semi-trailing arm in the rear.

All the advanced tech was great, but unfortunately NSU was not prepared for the issues which came along with its rotary engine design. The free-revving Wankel was overworked by zealous drivers, and after 1971 an audible warning was installed to let customers know when their engine was operating in the danger zone. Even if not stretched to the max, early engines had build quality and reliability issues. Many failed and required a rebuild before 35,000 miles. The problem was the motor’s rotor tip seals, which had to be redesigned to prevent internal leaks.

NSU’s engineers worked quickly, solving most of the Ro 80’s bugs by 1970. But by then dealer and consumer pressure had lead to a longer warranty on all cars, and it hurt the company’s reputation and wallet. No matter, as the Auto Union had taken hold and NSU was not long for the world. The Ro 80 continued in production at Neckarsulm through 1977. After that point, NSU was finished, and the factory was converted to Audi production. Today it makes the A6, A7, A8, and R8.

Today’s Rare Ride lived the first 15 years of its life as a standard sedan before it transformed at the hands of an Ro 80 specialist mechanic. Said mechanic desired a convertible NSU, and set to work in 1990 turning a four-door sedan into a two-door cabriolet. Another Ro 80 collector saw the drop-top and thought it an excellent idea. He hired the mechanic to build another in 1991. That’s where our beige Rare Rides Ro comes in — it’s the second of two converted. Yours for $13,000.

[Images: seller]

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16 Comments on “Rare Rides: A 1974 NSU Ro 80, in Convertible Form...”

  • avatar
    schmitt trigger

    The Wankel engine. Way ahead of its time.

    I don’t know whether using newer technologies, its major shortcomings could be overcome.

    • 0 avatar

      Well the Mazda RX-8 rotary was in production until 2012, so it used reasonably modern technologies — but the shortcomings were still there.

      • 0 avatar

        I’ve heard anecdotally that the RX-6/7 seemed to last longer if you drove them like an SOB.

        Personally I loved the RX-8s design with the clamshell doors etc. Too bad Mazda didn’t just drop their Turbo 2.5 in there and keep building it. I know that for RX enthusiasts the Wankel is part of the experience but I loved the practicality of the RX-8 design far more than the powerplant.

      • 0 avatar
        DC Bruce

        Aside from the tip seal problem, the rotary engine’s inherent problem is the relatively large interior area of the combustion chamber — which is thermally inefficient because of the heat loss that results. It’s also worth mentioning that today’s variable valve timing and lift technology, which maximizes efficiency at various engine speeds and loads, is unavailable in a rotary. The intake and exhaust ports are opened by the rotor at fixed points in the engine’s rotation, and for a fixed duration.

  • avatar

    How many Ro’s will fit on a ro-ro?

  • avatar

    Convertible top is a major fail. Looks like a Model A touring car. I don’t think anyone ever really got the tip seal problem really solved.

  • avatar

    Inflation adjusted the current asking price likely is less than the cost of the conversion!

  • avatar
    SCE to AUX

    “NSU’s engineers worked quickly, solving most of the Ro 80’s bugs by 1970.”

    That’s a relative term.

    Fifty years later, the bugs of the Wankel have never been worked out. It needs to stay dead, and not find fake new life (like Princess Leia) as an EV range extender.

  • avatar

    A work colleague from Germany told me that when two Ro80s passed on the road, the drivers would wave out the window and hold up fingers signifying how many times the engine had been rebuilt.

  • avatar

    Someone was inspired by the C3 ‘Vette, I guess. That, or a whole crapload of peyote.

  • avatar

    Holy scuttle shake, Batman!

  • avatar

    I didn’t see it in the article and am wholly unfamiliar with the creater of this contraption, but this looks more than a little French.

    Also, is 113hp out of ~1000ccs a good number for the period, or meh? Was this supposed to be why rotaries were so special; they could hit above their weight?

    What’s the saying, “the power of a V6, coming from an engine the size of a 4 cylinder, with the thirst of a V8”?

    • 0 avatar

      113hp per liter is a little more than the hp/liter of my 2.0T 2017 GTI Sport (220hp)! That was *astounding* for the ’60s. And the motor was very small and very light, and silly smooth running as well.

      Shame the various issues with the Wankel were not ever really solved. Mazda got pretty close, but fuel economy while meeting emissions standards remained a major issue.

      • 0 avatar

        OTOH you shouldn’t need a turbo to make 110 hp/liter unless you’re running on diesel.

        This Wankel may be described as having a liter of swept combustion chamber, but it also has three volumes defined by each rotor, so it should be called a 3 liter motor based on the volume of air and fuel it processes, incredibly inefficiently. The good thing about a rotary is that it is small and light physically. The bad things are that it drinks fuel like an engine nominatively three times the size and makes torque like an engine that uses a third as much fuel. Then there is the pollution that results from the necessary oil in the combustion chambers. It’s still good when you really need lots of high RPM power from a small, light engine. Not so good when you factor in the weight of the fuel though. It’s like an electric motor that pollutes locally instead of globally.

  • avatar

    I’ve always liked the Ro80, but this conversion is an epic failure.

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