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

We already do. Turbochargers use energy that would otherwise be wasted to pressurize the intake tract. This increases power and efficiency. It allows a small engine to do the work of a much larger naturally aspirated engine.

[A more in-depth explanation ](https://auto.howstuffworks.com/turbo.htm).