ArcaMax

The rotary engine's high specific output was (still is) achieved without a comparable increase in displacement. The original Cosmo's engine was smaller than many current motorcycle engines - just 982 cubic centimeters (less than 1 liter) for the original Cosmo's Series I rotary powerplant. Yet it produced a very respectable 110-130 hp. For some perspective, the Chevy Corvair - which was being sold around the same time as the Cosmo - had a six cylinder engine more than twice the size that made about the same power (90-110 hp).

By the time of the 1990s-era RX7, the rotary engine was making nearly 300 hp (when turbocharged) out of 1.3 liters. This is one of the highest output-per-liter-of-displacement ever achieved.

Mazda dialed back the power some when the RX8 replaced the RX7 in 2001- but the 1.3 engine was still producing 232 hp when ordered with the six-speed manual transmission. But, there was a hair in the soup. Three, actually.

First, the rotary engine was - and still is - shockingly thirsty for a such a small engine. By 2011 - the final year for the RX8 - the window sticker read 16 city, 23 highway. Many V8s three times the size use less fuel. And most motorcycle piston engines of about the same size deliver twice the fuel-efficiency.

By itself, this probably would not have been a deal-breaker. Fuel economy is a big consideration for economy car buyers, but sports car buyers are usually willing to overlook a rapidly draining tank if the car delivers the goods. Which the RX8 absolutely did. It was quicker (and faster) than Mazda's other sports car - the hugely popular but somewhat slow-pokey Miata. And it handled better than the Miata, because of the rotary engine's behind-the-front-axle location - which conferred closer to the sports car ideal 50-50 weight balance.

That plus a sport bike engine's capability to rev close to five figures endeared the car to enthusiast buyers. But the car's hungry hippo appetite was a problem for Mazda - because of federal fleet fuel economy mandates (CAFE, in the vernacular of regulatory officialdom). Each 18 MPG (average) RX8 that got built lowered Mazda's fleet average fuel economy numbers - which incurred gas guzzler fines if the number dipped below the then-in-effect 27.5 MPG average decreed for passenger cars.

With a 35.5 MPG - average, remember - mandatory minimum on deck for model year 2016, the RX8's appetite was as much in the spotlight as Caitlin Jenner is right now. And the dilemma for Mazda was that in order to increase the rotary engine's fuel-economy, it would be necessary to make changes to the rotary engine's design that would likely increase its emissions of politically incorrect gasses.

Sealing problems had long been - and continue to be - the rotary engine's Achilles Heel. Piston engines use multiple expanding rings around each piston to maintain compression and prevent oil from getting into the combustion chamber, where it would otherwise be burned along with the incoming air-fuel charge and then sent hence via the tailpipes to the surrounding air. Also, there are tulip valves (with seals) that control the flow of intake and exhaust charges - vs. the fixed-in-place ports that are covered and uncovered as the rotor spins.

The rotary engine depended on seals at the tips (apex) of each rotor to contain combustion gasses but these seals were prone to leak as well as to leak sooner rather than later, especially under hard use. The ports were also an issue, emissions-wise as there tended be overlap between cycles and some of the "bad" gasses - especially unburned hydrocarbons - tended to escape into the atmosphere. It was not a big deal initially.

When the Cosmo came out in the late '60s, blue smoke was as common a sight as bell-bottomed hippies in San Francisco. It was legal to sell engines that burned oil on purpose (the famous two-stroke sport bikes of the late '60s and early '70s) and in general the public didn't give a damn. So long as the thing ran like stink it was ok if it actually did stink.

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