Precious few engine configurations have the power to split opinion amongst car folk quite like the rotary, or to give it its proper title, the Wankel. You likely all know the basics of the engine even if you don’t necessarily possess the engineering nous to describe its function in detail, but in some respects that’s all you need: a three-side, roughly triangular rotor, spinning away within the confines of the oval combustion chamber in which the Otto cycle takes place.
Another thing you likely all know about rotary engines, is that they can be complex, thirsty (for both fuel and oil), and have the potential to sound like the devil himself, assuming said demon has first been doused in in Shell Optimax, set alight and forced to stamp (barefoot) upon sharpened Lego bricks of course!
The complexities associated with rendering a rotary engine suitable for mass market use have long proved a barrier to their mass adoption, their relative lack of frugality making them harder to justify for contemporary car makers keen to foreground their ‘green’ credentials. It has also proved hard to entirely trust the general, car-buying public to take proper care of an engine as intolerant of patchy, laissez faire maintenance as the ‘spinning Dorito.’
Not that any of this has prevented several car makers from persevering with the concept, many of them with interesting (if ultimately unsuccessful) results, and we’re not just talking Mazda and NSU here – though both do grace the list below, just for balance. Enjoy this selection of left field, oddball rotary failures…just don’t mention the apex seals.
This, believe it or not, is genesis; the NSU Spider became the first car to be sold with a Wankel engine when it was released in 1964, and at the time it was thought by many to herald the arrival of a new era for internal combustion cars. The Spider was based upon the NSU Sport Prinz and thus retained its rear-engine layout, albeit with a 50bhp Wankel providing the motive force as opposed to an inline two.
Mazda – Roadpacer
Yes, it’s a model from the company most closely associated with the rotary engine, but the Roadpacer is weird even by Mazda’s own, gloriously unhinged standards. The Roadpacer was actually a Holden Premier – yea, those Aussies known for shoehorning V8s into small saloons and coupes, and as such it represented a marked departure from the norm for both firms.
The move was intended to allow Mazda to offer a top-spec flagship sedan but with an engine (the 13B) better understood in its native land than Holden’s ‘Red’ inline six, which it was. It was also underpowered at 130bhp, overweight at 1575kg, and as a result returned abysmal fuel economy – 8-10pmpg abysmal. It remains the only GM product to have been offered with a rotary.
Citroen – M35
Pre-PSA Citroen was in a decidedly odd place, having recently bought Maserati and agreed to form a sub-company with NSU called Comotor. This was an attempt to make the latter’s Wankel engine a viable prospect for sale to the mass market (see the GS) but doing so required the firm to build a proof of concept, which is how the world ended up with the wonderfully bizarre M35.
The M35 was powered by a 995cc single rotor Wankel rated at just under 50bhp, which in turn resulted in a 0-62mph dash of 19 seconds – a full 10 seconds faster than the Ami 8 on which it was based. A mere 267 were built before the plug was pulled in 1971, after which Citroen attempted to buy back as many as possible to save itself from ruinous warranty costs.
Datsun Sunny RE
A plethora of car makers began to beat a path to NSU’s West German front door in the late sixties, all convinced of the Wankel’s ability to delivery smooth, near silent propulsion – this was by no means a Mazda only affair. Indeed, Mazda weren’t even the only Japanese car maker interested in the Wankel, its arch rivals at Datsun also dabbled with the concept, coming up with the Sunny RE prototype of 1972. The PB110 shape car ran a twin-rotor design supposedly good for 120bhp – not to be sniffed at in a pre-hot hatch era, when a ‘quick’ car was something with just over 100bhp. Sadly for those of us with a hankering for an OEM rotary Sunny, the concept never made production.
Citroen – GS Birotor
What do you get if you cross a car company with a reputation for excellent (if somewhat fragile) engineering but little in the way of funds, an engine little understood outside of enthusiast circles, all filtered through the global fuel crises of the early seventies? The Citroen GS Birotor, of course!
The car itself was the result of a brief flirtation with Wankel technology on the part of Citroen (with help from NSU), and while the end result was a smooth, refined and more powerful GS, it was also ruinously expensive to buy and run. It also had the misfortune to be born into the aforementioned oil crises of 1973 and was thus condemned to failure at a stroke.
Mazda spent a good portion of the seventies trying to cram rotary engines into anything that came within range, and as such it wasn’t all that surprising when it attempted to do the same with its B-Series pickup following the USA’s light truck ‘boom’ of the same period. The resulting vehicle was designated REPU – Rotary Engined Pick-Up, and was powered by yet another 13B.
Sadly for those taken by the idea of a manic, multi-rotor pickup, the REPU was not a commercial success; the 13B proved lacking in torque and low-down power, both of which are generally considered vital for any truck. None of these factors stop the REPU being one of the coolest Mazdas of all time, and the coolest entry on this list by a massive margin. Probably.
Mazda Eunos Cosmo JC
Come the late eighties, and it had become painfully clear that the average consumer wasn’t especially taken with the concept of the rotary, thanks in part to terrifying tales of their thirst for oil and fuel, and of course somewhat patchy reliability. Mazda weren’t quite done with the concept however, and in fact doubled down on its commitment to the Wankel concept with its 787b Le Mans racer, and for the road, its Eunos Cosmo.
The Eunos Cosmo was intended to be Mazda’s halo car and sat atop the range, functioning as a left field (very, very left field) Japanese alternative to the traditional executive offerings from Germany. None of this would’ve been especially noteworthy had the Cosmo not been powered by the most powerful rotary engine ever fitted to a production car, the triple-rotor, twin-turbo, 300bhp 20B.
Mercedes-Benz – C111
C111 actually referred to a run of sixteen experimental prototypes built by Mercedes in the late sixties and early seventies, each a means of assessing the viability of a given technology for mass production. Thirteen of the C111s produced were powered by Wankel engines, the all but forgotten yet deeply cool M950F, ranging in power from 280bhp for the trip-rotor to a massive 350bhp for the final, quad-rotor version.
Poor fuel economy, coupled with the effects of the oil crises in ’73, eventually convinced Mercedes to bench its rotary programme.
Lada – Various
As if to underscore the fact that pretty much anyone and everyone dabbled with the Wankel at some point or another over the course of the 20th century, we have Lada’s effort – the VAZ-311 and later a twin-rotor, the VAZ-411. Both made substantially more power than their reciprocating piston relations (120bhp in the case of the 411), and as such both were predominantly used by the Soviet secret police, the KGB.
A triple-rotor called the VAZ-431 also existed, supposedly good for 280bhp and the sole preserve of high-ranking secret service officials. You know, the sort high enough up the KGB-tree to have someone else to do their fingernail-pulling for them. There were even rumours of an experimental quad-rotor called the VAZ-543 with almost 350bhp, though concrete information on this application is almost non-existent.
Chevrolet Corvette XP-897 GT
Think Corvette, think V8 – GM’s sports car is effectively a stand-in for America itself at this point, and as such picturing a Corvette – and Corvette – with anything other than a big, lazy, naturally aspirated V8 is just weird. But it hasn’t always been this way, and for the briefest of moments in the late sixties there existed the briefest of windows for a Wankel-powered Corvette, the XP-897 GT, the concept shown above.
Not only did the GT draw its power from a twin-rotary, said engine was mounted amidships in order to better aid packaging and to make the completed car (if it had made production) easier to sell in Europe. It never got that far, clearly, but the combination of 180bhp, mid-engined-transaxle layout and a Pininfarina-penned body make you question why this was ever the case.