When you think of the rotary engine, what kinds of things jump quickly to your mind?
Let me try a few: Mazda, thirsty, rev-happy, oil-burning, RX-7, RX-8, quirky, Wankel.
How about dead? After 45 years, one of Mazda’s most identifable traits has hummed off into the sunset, as the company built the last RX-8 last week.
The rotary engine, invented by Felix Wankel in Germany after World War II was a miracle of packaging. It occupied a fraction of the under-hood space that a comparable piston engine would. Mazda exploited this packaging advantage in developing some of its sports cars over the years, the most famous of which was probably the two-seat RX-7. That model, produced from 1978 to 2002, boasted sleek looks, balanced handling, and light weight – attributes (aside from perhaps the sleek looks) which carried over to Mazda’s wildly successful MX-5 Miata beginning with the middle of the RX-7’s production.
Automobile companies once saw the Wankel engine as a potential solution to the reliability problems that were very prevalent in the late 1960s/early 1970s, because Wankel engines can rev smoothly at extremely high speeds and had proven durable in testing. It was an open secret that GM was developing a two-rotor Wankel engine for the then-new Vega in the early 1970s, but emission and fuel economy performance plagued the engine (and right in the midst of the Arab oil embargo and implementation of the Clean Air Act). After only a few years – and with no major manufacturer actually installing Wankel engines in a production car – the interest subsided. Except at Mazda.
Boning up on the history of the GM Wankel program, it’s remarkable that many of the same issues that torpedoed the engine for GM – primarily emissions and economy – are basically what caused the engine’s demise at its long-time patron, Mazda. In 2010, the RX-8’s engine failed strict Euro 5 emission requirements, so the car could no longer be sold in Europe. Slow selling in North America and in its home market, Mazda pulled the plug after building less than 3,000 cars in 2010.
Experts attribute the Wankel’s poor fuel economy and emissions to the fact that the engines required oil injection to lubricate seals, and proportionately more fuel was left unburned relative to other engines. So more unburned hydrocarbons were coming out of the tailpipes, which pollutes and means they’re not burning and, you know, actually propelling the car.
It’s a shame to see the RX-8 ride off into the sunset. I had a chance to drive one just once, but it was on a track. The car was so light (about 3,000 pounds) and had almost magical-feeling steering, but the rotary engine has very little low-end torque, so you need to rev it like crazy and keep up your momentum in order to drive it quickly. If you could pull that off, though, you were rewarded with a car that just loved to be thrown around curves.
In an era of ever more strict fuel-economy and emission regulations, it’s hard to imagine the Wankel engine ever finding a place in the mainstream (or in Mazda’s case, on the fringes of the mainstream) auto market. The engine’s best hope might be as a very compact range-extending engine in a plug-in car similar in concept to the Chevy Volt, where fuel economy isn’t as important as space efficiency (less engine space = more battery, passenger, and cargo space). We’ll have to see if Mazda has any plans for the future of one of its signature technologies, but for now, it seems that the future for Mazda is light weight chassis and high-compression piston engines under the SkyActiv brand.
After more than two million Mazda vehicles produced with rotary engines (including an incredible 239,871 in 1973, when Mazda put the rotary in things like trucks and family sedans), it appears that the last chapter of the rotary has been written. But its obituary has appeared before numerous times, so we’ll have to see if there is a resurrection in a few years.