Setting aside for a moment the many
environmental issues associated with the
internal combustion engine, let's think about this
device in further detail.
Internal combustion technology has undergone over a century of refinement and redesign, and it shows. The modern gasoline engine is a computerized, fuel-injected, precision-machined marvel of evolutionary engineering. You can drive a new car for thousands of miles with nary a hitch, which is almost unbelievable considering the complexity and sheer number of parts that go into a modern engine.
Consider, if you will, the issue of intake/exhaust valve actuation schemes.