Can you put a small engine in a car.?

Could it be possible to put a small engine like a lawn mower engine into a real car. Could it be possible to drop the engine, and lighten it up to run off a small engine like http://smallenginewarehouse.com/product.asp?PN=CH1000S-0002&desc=Kohler%20Engine%20%2040hp%20Command,%20Hor%201-7/16%22x4-29/64%22%20Shaft,%20Fuel%20Pump,%20Oil%20Cooler,%20Throttle%20Control Could this work in a car like a geo or a old VW beetle