Ask an enthusiast about air-cooled engines and the conversation will quickly land in Porsche 911 territory. Though not the only car to ever feature an air-cooled engine, looking at you, VW Beetle ...

Air-cooled engines were once commonplace in the auto and moto industries. The most well-known were the Porsche flat six, VW flat four, Corvair, and numerous motorcycle engines, from BMW to Harley ...

In its mid-1960s configuration, the air-cooled VW engine was a 1.2-liter boxer four cylinder that put out around 40 horsepower, according to Autoweek. But it was made in a few other displacements ...

As the air-cooled models were phased out, this engine became VW's primary model. The first EA827 4-cylinder engines were fed by carburetors, but VW adopted fuel injection by the end of the '70s.

How much did the air-cooled Volkswagen Beetle change in its 30-year U.S. history? We drove the oldest and (near) newest examples to find out.

By far the most common and best-known air-cooled car is the original Volkswagen Beetle, and I've often wondered about if VW ever experimented with water-cooled engines in the old-school Beetle.