The air-cooled engine has had a long and well-loved history. At least, depending on whom you talk to. In the 1960s and 1970s some carmakers used air-cooled engines to power their vehicles. The 1964 Porsche 911 may be one of the fastest air-cooled engines, but the Volkswagen air-cooled engine may be one of the most beloved. It was used in the original Beetle.
You'd be hard-pressed to find an air-cooled engine rolling of the auto assembly line these days, but that doesn't necessarily mean they're anywhere near dead.
If you hop on a motorcycle, all-terrain vehicle, or even a common riding mower then you're probably experiencing an air-cooled engine (although some motorcycles are liquid-cooled). But it's aircraft that have had the longest running air-cooled track record because many helicopters and small planes have remained air-cooled right from the beginning.