Why can’t we use the heat from combustion to make cars more efficient?

Question

Can we use the heat to boil water to turn a turbine? Or would the water never cool enough to be used again?

What about using the heat to create pressure and then releasing the pressure to help move the fly wheel?

In: 1046

Answer 1

This may not be exactly what you meant, but cars _do_ use the heat from the engine to be more efficient. Namely, when you turn on the heater in your car, it’s using heat extracted from the engine (via the coolant) to heat your car “for free” rather than requiring any alternative heat source.