Why don’t they put radial engines in cars?
Too complex, not space or mass efficient, hard to cool, hard to work on. Even horizontally opposed piston engines have some of these problems, only Subaru and Porsche use them, as far as I know. Most car engines have their pistons arranged inline, or in two inline banks making a V.
Why are radial engines used in cars?
This is useful in airplanes because you can put a bunch of cylinders right at the nose of a plane and the air cools them all equally. In cars, it’s less useful, though, because it’s a big lump of engine to design around.
Why are radial engines in cars?
The radial aircraft engines provided greater power-to-weight ratios and were more reliable than conventional inline vehicle engines available at the time.