The rotary engine

Hmmmm," went the rotary engine in Mazda's TV ads. "Boingety, boingety, boingety, boingety," went everyone else's.

The rotary engine was developed by German engineer Felix Wankel and first used in a German NSU passenger car in 1957. Versions of the engine are still used in small pumps and compressors.

Several Japanese automakers licensed the technology in the 1950s. Its tiny size, light weight, high power output, and simplicity gave the engine great promise. Mazda was the only other company to put a rotary on the road. In 1971, Mazda entered the United States market with a line of small, rotary-engine-powered cars.

Those early rotaries spewed gas and oil and rarely lasted 50,000 miles. As US emissions requirements tightened in 1973, Mazda had to add an afterburner to burn off raw fuel that leaked past ineffective seals. As the first gas crunch fell, buyers fled the rotary. Mazda began using traditional piston engines.

By 1978, in Mazda's RX-7 sports car, the company had perfected the seals and found a fitting market. Fuel economy improved. The afterburner wasn't needed.

In the 1980s and '90s, the RX-7 followed other Japanese sports cars upmarket. Sales dropped. Mazda pulled its super sports car - and its rotary engine -out of the US market in 1993. Now part of Ford, Mazda says it will bring back the rotary by 2004. It showed a rotary-powered four-door sports car in Tokyo last year.

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