How Mazda’s Luxury Sleeper Got Three Rotors Past Every Regulator
Ah, the Wankel rotary engine. One of the most fascinating forms of internal combustion, yet one that pretty much every automaker had moved on from by the ’80s, owing to reliability issues, poor efficiency, and ultimately the ever-more-difficult task of getting them past regulators.
Except for Mazda, which persisted with rotaries when everyone else had given up on them. While the rotary production car everyone loves and remembers is the 13B-powered FD RX-7, the most fascinating came in the form of a halo model with a tri-rotor engine that nobody could’ve expected.
A Brief History Lesson On The Wankel Rotary
Before that, though, a quick history lesson on the Wankel rotary engine. Invented in the 1950s by German engineer Felix Wankel, these strange engines use a rotor to manage the suck, squeeze, bang and blow of a combustion engine.
While most internal combustion engines use pistons that sit on top of a crankshaft for up-and-down movement, the rotary’s rotor sits on an eccentric shaft that rotates the affectionately named Dorito. Air and fuel are fed into an intake chamber at one side of the rotor, which is then drawn toward another to compress the mixture, with the spark plugs igniting it and ultimately causing the shaft to rotate, while the final side deals with exhaust gases. Over, and over, and over.
The first production car to use this type of engine wasn’t a Mazda, despite its association with rotaries. Rather, it was the NSU Spider in 1964, born from a company that would eventually merge to become a part of Audi.
Mazda Didn’t Stop The Rotary, Even When Everyone Else Had
NSU was the first to put a rotary into production, with Mazda soon following in 1967 with the Mazda Cosmo sports car. French manufacturer Citroën would put a two-rotor version of its GS on sale as well at the end of the decade, while other manufacturers toyed with the idea of using a Wankel.
Most famously, the Mercedes C111 concept cars had three- and even four-rotor engines at one point, while General Motors put a lot of time and effort into developing a rotary for the Vega and threw a Wankel into a couple of Corvette prototypes. None of those cars would enter production, though.
It wouldn’t take long before the rotary almost entirely disappeared from production as well. The collapse of NSU came about when the Ro 80, its second rotary car, suffered serious reliability problems that destroyed the company’s finances with warranty replacements, and the newly formed Audi would ditch the Wankel.
Likewise with the Citroën GS, causing the French manufacturer similar grief, though not enough to put an end to it entirely.
Yet, none of that stopped Mazda. While its rotaries were known to need more frequent care and maintenance than those of conventional combustion engine cars, it had made the Wankel a USP of its own. After the Cosmo, rotary engines would go on to feature in pretty much all of its conventional road cars and most famously under the hood of its RX-series of sports cars.
The RX-7 epitomized the rotary, with the twin-rotor 13B-REW found in the FD Mazda RX-7 widely considered the pinnacle of them all. Yet, for those in the know, there’s an incredible model with an extreme rotary engine that sits even above the FD.
The Three-Rotor Halo Model That Nobody Expected
Now, for another little detour, this time to the Japanese economic bubble of the ‘80s. With lots of money to throw around and plenty of customers willing to spend it, things got very, very experimental in the Japanese automotive industry.
For Mazda, that meant establishing a new luxury brand designed to be the pinnacle of its models. Eunos was the name, and it would cater exclusively to sporty and luxurious cars, with the NA Mazda Miata sold in the country as the Eunos Roadster, for example. Meanwhile, sedans like the 500 and 800 were aimed squarely at the aspirational businessman. Curiously, the RX-7 would be marketed under Efini, but that’s for a different day.
Then, in 1990, the halo model of the flagship Eunos brand came from almost nowhere. This was the remarkable Eunos Cosmo, a luxury Grand Tourer designed to showcase the pinnacle of Mazda’s engineering capabilities.
You had a choice of two engines when it came to the Eunos Cosmo. The entry-level model (if you can call it that) used the two-rotor, 1.3-liter 13B-REW seen in the RX-7, but this isn’t the one that truly stood out.
That honor goes to the utterly bonkers 20B-REW. This was a 2.0-liter, tri-rotor engine (the only one of its kind to be fitted to a production car) that used twin sequential turbocharging for an official output of 276 horsepower and 297 lb-ft of torque. While that may not sound like a halo-worthy power figure, it had to be capped at that on paper to meet the Japanese Gentleman’s Agreement, meaning production cars from the country couldn’t exceed 276 hp.
Yet, because of its heavy focus on performance and complex engineering, it proved to be quite inefficient even by the standards of rotary engines. Not necessarily a problem for the wealthy Japanese businessmen the cars were targeted at, and the country’s displacement-focused tax system worked in favor of the power-dense and relatively low-capacity rotary engine despite its impressive performance, but it made the car virtually impossible to homologate outside of the country.
Despite that, it had technology that would be a global first, and would mark it with a unique place in history.
It Wasn’t Just The Engine That Was A World First
Not only was the Eunos Cosmo a showcase of what Mazda engineers could do with virtually no restrictions on engine development, but also the tech it could cram into a flagship luxury model.
Notably, the Eunos Cosmo was the first-ever production car to be fitted with a true GPS-based satellite navigation system. Other models before it had used other forms of navigation, but the Eunos Cosmo pioneered GPS, which wouldn’t appear in the States until 1995 when Oldsmobile launched Guidestar. That navigation was displayed on an LCD touchscreen infotainment system, which was also used to manage climate control, the trip computer, and radio. In 1990. It has only been in the last few years that most mainstream models have caught up to that precedent.
Beyond that, it had some very clever chassis technology, with double-wishbone suspension on both axles, four-wheel steering, and even four shock absorbers on the rear axle to create a comfortable ride.
It’s A Rare Beast, But Should You Buy One?
Naturally, all of this technology, innovation and an extremely complex engine made the Eunos Cosmo an expensive car. The 13B-powered Type S started around the equivalent of $22,000 while the 20B Type E was around $35,000. Today, that’d be the equivalent of around $60,000 and $100,000.
That made it quite a rare car. It’s thought 8,875 Eunos Cosmos were produced, with just under half of those being the truly desirable 20B-powered cars.
All produced are now comfortably within the age threshold for US import, and a few examples have found their way Stateside already as a result. They don’t come up for sale very often, but when they do, expect to pay north of $10,500 for a well-kept 13B and as high as around $25,000 for a 20B. Prices of cars in Japan are in a similar ballpark, but you’d also need to consider shipping and import fees.
However, you should consider how difficult it will be to keep an Eunos Cosmo running in the US. Support for the 13B is relatively common, given its appearances in the RX-7, but the 20B was exclusive to the Cosmo and parts availability is extremely scarce, even if you’re looking in Japan. Not to mention its complex suspension setup and seriously cool but obsolete interior technologies.
For any rotary collector, though, those compromises are worth accepting for such a unique piece of automotive history.
Sources: Mazda
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