Is fuel cell or car engine more efficient, and what different emissions do they give off?

Question

Is fuel cell or car engine more efficient, and what different emissions do they give off?

Answer 1

Hydrogen fuel cells are slightly more efficient, at 40% whereas an internal combustion engine is closer to 25% efficient.  However, when you include all the other energy losses for a hydrogen fuel cell car (i.e. producing the hydrogen), it's only about 25% efficient overall, so they're about equal.

In comparison, an electric motor has 86% grid-to-motor efficiency.  See the link below for further details.

Answer 2

your engine is more efficient then the fuel cell