Doing things differently
The powerful, compact and high-revving rotary engine of the type dreamed up by Felix Wankel has fascinated more car manufacturers than you might imagine.
Even Rolls-Royce, stretching the idea to its limit, worked for a while on a diesel rotary for military vehicles.
Very few cars with rotary engines – most of them created by Mazda, as pictured – actually made it into production in the 20th century.
Since our list would otherwise be quite short, we have therefore included several (though not all) racing cars and concepts, along with a few production models which were at one time intended to be sold with rotaries, even though this never actually happened.
A brief explanation
Like piston engines, rotaries take in a fuel/air mixture, compress it, combust it to release energy and then expel the resulting exhaust gases.
All of this is made to happen by one or more rotors spinning eccentrically round a central crankshaft in an approximately figure-of-eight chamber. The crank spins three times faster than the rotor, and there are three complete power cycles for each turn of the rotor.
A rotary’s advantages include smoothness (the rotors do not stop in mid-cycle, as pistons do), a very small number of moving parts and almost constant power delivery.
On the flip side, fuel intake and exhaust emissions are almost constant, too, and sealing the rotors within their chambers is very difficult to achieve. This is why rotaries are still rare, even though they have been around for nearly 60 years.
1. Alfa Romeo Spider/1750
We are, of course, starting this alphabetical list at A…
Alfa Romeo ran a development programme for single- and twin-rotor engines before deciding to drop that idea in 1973, because of those reliability and fuel consumption problems which you’ll be hearing about again several times.
A Spider sports car (representative model pictured) and a 1750 saloon were fitted with the experimental units, but no production cars were built.
A twin-rotor engine has survived, though, and is kept at the Alfa Romeo Museum in Arese, Italy.
2. AMC Pacer
The Pacer is widely regarded as one of the oddest mainstream cars of the 1970s.
It would have seemed odder still if it had been sold with a rotary engine, as AMC originally intended.
Believing that the rotary was the power source of the future, AMC first acquired a licence to build its own, then arranged a supply deal with General Motors.
When GM decided to abandon its rotary project, AMC was left out in the cold. The Pacer had to be adapted to take the company’s long-standing straight-six – and later a 5.0-litre V8.
3. Chevrolet Aerovette
The Aerovette concept of 1973 was a study for what would have become a mid-engined Corvette, though that idea did not make it to production until 2020.
The Aerovette had two engines, though not at the same time. It started out with a quad-rotor reputedly capable of producing more than 400bhp, but various problems including the global oil crisis and increasingly stringent emissions regulations (neither of which favoured rotaries) persuaded GM to stop development.
A few years later, the car, which is now part of the GM Heritage collection, was fitted with a 6.6-litre smallblock V8.
4. Chevrolet Monza
The Pacer and the Aerovette were not the only cars originally planned to use the GM rotary engine.
Another example was the Monza, which might have gone on sale with the same two-rotor unit intended for the Pacer.
Production began in late 1974, by which time GM had abandoned the rotary project.
5. Chevrolet Vega
From 1970 to 1977, the Vega was sold with a variety of four-cylinder piston engines, one of them developed by Cosworth.
1970 was too early for a rotary version, but there was talk of one going on sale in the 1974 model year.
As with the cars previously mentioned, though, GM’s rotary dream was a thing of the past before customers had a chance to buy this one.
6. Citroën GS Birotor
Alphabetically if not chronologically, the first production car on our list looked very similar to the regular GS.
Its engine, however, wasn’t the usual flat-four, but a twin rotor developed by Comotor, a Luxembourg-based joint venture involving Citroën and NSU.
The car was launched in 1973, three years after regular GS production began. This was also the time of the global fuel crisis, and the combination of terrible economy and an enormous purchase price killed the Birotor within months.
Its engine was later used in a very odd-sounding helicopter, but that project crashed (though the helicopter itself didn’t) when Citroën went bankrupt in 1974.
7. Citroën M35
The GS Birotor was preceded in 1969 by the M35, a coupé derivative of the Ami which looked even stranger than the regular version.
Unlike the later car, it was powered by a single-rotor Comotor unit.
Well over 200 were built. Customer evaluation persuaded Citroën that a future model might be successful, which turned out not to be the case.
8. Eunos Cosmo
Unlike all the others, the last-generation Cosmo built by Mazda was marketed by that company’s upmarket Eunos brand, which was in operation for most of the 1990s.
As will become apparent later, Mazda was by now very familiar with rotary engines, but the unit in this car was unusual in having three rotors, along with twin turbochargers.
Respecting an agreement among Japanese manufacturers at the time, the engine had a quoted maximum power output of around 280bhp.
Another surprising thing about the Cosmo was that it had satellite navigation, an extraordinary feature for a car which went out of production in 1996.
9. Lada
Although this may come as a surprise to westerners, AutoVAZ fitted several of its cars with rotary engines over a long period starting in the late 1970s.
These included several versions of the ‘classic’, Fiat 124-based Lada (representative model pictured), and of the later Lada Samara.
Build numbers were low, and many examples were unavailable to private customers, but they were certainly production models.
10. Mazda 787B
Mazda competed in sports-car racing with a series of rotary-engined machines, usually with limited success.
Things were not expected to improve in 1991, when the manufacturer turned up at Le Mans with three 787Bs, none of which made it into the top 10 in qualifying.
However, the cars performed splendidly in the race – particularly the one driven by Bertrand Gachot, Johnny Herbert and Volker Weidler, who won by two laps against mighty competition from Jaguar, Mercedes-Benz and Porsche.
It was the first – and, to date, only – Le Mans race won by a rotary-engined car. Mazda’s involvement came to an end following a rule change for 1992, which restricted the engine choice to piston units of up to 3.5 litres.
11. Mazda B-series
Already nearly a decade old, the second-generation B-series pick-up was introduced to the US and Canadian markets in the 1974 model year with the new (and eventually very long-lived) twin-rotor 13B engine also available in the RX-4 saloon, among others.
The Rotary Pickup, as it was called, was praised for its quiet, smooth running, which contrasted notably with the sound of the four-cylinder piston engines which dominated the class.
Sales were promising at first, but collapsed when the rotary’s poor fuel economy came face-to-face with the global oil crisis.
12. Mazda Cosmo Sport
Mazda’s first production rotary car was unveiled at the 1964 Tokyo motor show, three years after work had begun on its twin-rotor engine.
It probably wasn’t mentioned at the time, but the Mazda engineers were struggling to avoid the rotor seal tips gouging the inner walls of the rotor housing and creating what became known as ‘the devil’s claw marks’.
The problem was eventually solved, and the Cosmo Sport went into production in May 1967.
The Series I was replaced the following year by the more powerful Series II, which was discontinued in 1972.
13. Mazda Luce
The Luce, known as the 929 in export markets, was produced in five generations from 1966 to 1991.
Rotary engines were available in every generation, including the very rare Bertone-designed R130 coupé of 1969 (pictured). This was Mazda’s first front-wheel-drive model, and the only Luce with that mechanical layout.
The third Luce shared its platform with what Mazda refers to as the second-generation Cosmo, not counting the original Cosmo Sport.
14. Mazda R100
Mazda built the Familia for nine generations from 1963 to 2003. The second of these generations was the only one to include a rotary engine, and those cars were known in export markets as R100.
Available from 1968 as a saloon or a coupé, the R100 had a detuned version of the twin-rotor engine used in the Series II Cosmo Sport, though its power output could be nearly doubled in competition versions.
It was Mazda’s first volume-selling rotary car, and paved the way for the first model in the long-running RX series.
15. Mazda Roadpacer AP
The AP part of this model’s name stood for Anti-Pollution, a strange choice given the inherent exhaust emissions problems common to rotary engines.
This large saloon was far from being Mazda’s most successful rotary, with a brief production run in the mid 1970s. Both buying the car in the first place and throwing fuel at it from then on cost customers a lot of money.
Over in Australia, Holden was much more successful with the Premier, which was the same car fitted with a more powerful straight-six engine.
16. Mazda RX-2
The RX-2 was the rotary version of the Capella, and was known in Japan, straightforwardly enough, as the Capella Rotary.
It was launched in 1970, the same year that Mazda first exported rotaries to Europe and North America.
By the end of that year, Mazda’s production of rotary models had reached 100,000.
17. Mazda RX-3
Smaller and sportier than the RX-2, the RX-3 made its Japanese debut in September 1971. Once again, the name referred to export cars. In Japan, it was sold as the Savanna, which indicated that it was the rotary version of the model known at home (when fitted with a four-cylinder piston engine) as the Grand Familia, and elsewhere as the 818.
The RX-3 Sports Wagon, launched in 1972, was the world’s first rotary-engined estate.
Production continued until 1978 and was divided into three series, with various styling changes and equipment upgrades from one to the next.
The RX-3 was very successful in motorsport around the world, and popular in standard form. In its peak year of 1973, 105,819 examples were sold. With a lifetime figure of 286,757, it was the second highest-selling Mazda rotary to date, beaten only by the later RX-7.
18. Mazda RX-4
Following a by now familiar pattern, RX-4 was the export name given to the rotary-powered version of the second-generation Luce.
Larger than either of the previous RX models, it made its debut in late 1972 as a saloon or a coupé. An estate body style was added to the range the following year.
While it never found as many as 100,000 customers in a single year, the RX-4 outsold the RX-3 from 1974 onwards, though its lifetime total was lower.
19. Mazda RX-5
The Mazda Cosmo launched in October 1975, six months after the Roadpacer AP, was marketed as the RX-5 outside Japan.
Four-cylinder engines were available, but the power source we’re interested in here was a twin rotor.
This was the longest and widest of the 1970s RX-series cars, though considerably smaller than the Roadpacer. In 1978 it was replaced by the most popular RX of all.
20. Mazda RX-7
Although it was only ever sold as a two-door coupé, the RX-7 is the longest-lived and best-selling rotary car in history, with 811,634 sales across three generations from 1978 to 2002.
The first-generation model was exceptionally successful in motorsport, and memorably noisy when fitted with the megaphone type of exhaust which works well with rotary engines.
Win Percy won the British Touring Car Championship in both 1980 and 1981 with an RX-7. Other examples performed extremely well in American, Australian and European racing, winning the 24-hour events at Spa and Daytona along with IMSA and Australian Touring Car Championship titles. A Group B version was also developed for rallying, and finished third in the 1985 Acropolis.
The RX-7’s successor was the RX-8, which we’re not including here because it wasn’t sold in the 20th century.
21. Mercedes-Benz C111
The first in the series of C111 experimental cars was unveiled at the Frankfurt motor show in 1969.
Unusual features included a very low body, gullwing doors, a mid-engined layout and a three-rotor engine producing around 280bhp. This was replaced over the winter with a quad-rotor with an output nearer 350bhp.
Nearly all of the 12 cars built were rotaries, but Mercedes-Benz eventually decided this was not the way forward, and replaced those engines in some examples with various V8s of up to 4.8 litres. The last car, built in 1975, had a 3.0-litre diesel.
22. Nissan Sunny
Like several other manufacturers, Nissan showed some interest in rotaries in the late 1960s and early 1970s.
A twin-rotor version of the second-generation Nissan Sunny coupé (representative model pictured), known outside Japan as the Datsun 1200, was unveiled at the 1972 Tokyo motor show.
Unfortunately for rotary enthusiasts, the project went no further. The second-generation version of the larger Silvia was also intended to have a rotary engine, but this did not make it to production either.
23. NSU Ro80
With its dramatic looks, impressive aerodynamics, all-round disc brakes, front and rear independent suspension, and a clutch controlled by touching the gearlever, the Ro80 was so impressive that it easily won the 1968 Car of the Year award.
Its only serious problem was the early unreliability of its twin-rotor engine. This was eventually fixed, but the damage had been done.
The Ro80’s poor reputation, compounded by its thirst for fuel at a time when oil prices were rising sharply, killed not only the car, but the NSU brand as a whole.
After 1977, when the Ro80 was discontinued, there were to be no more NSUs.
24. NSU Spider
The Ro80 was not NSU’s first rotary-engined car. That honour instead goes to the beautiful little Spider, derived from the markedly less beautiful Prinz saloon.
The Prinz was only ever powered by piston engines, but the Spider had a tiny single-rotor unit mounted in the rear.
It was introduced in 1964, the same year as the Mazda Cosmo Sport, and was built in small numbers until 1967. As well as being a very attractive road car, it was also competitive in various forms of motorsport.
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