## Conceptual Physics (12th Edition)

As discussed on page 345, Carnot's equation states that the ideal efficiency of a heat engine is $\frac{T_{hot} – T_{cold}}{T_{hot}}$. Mathematically speaking, increasing the difference in temperature allows the engine to be more efficient. Applying this theory to a car engine, we learn that burning fuel at a higher temperature (as is done in a diesel engine) or lowering the temperature of the car's environment both increase the engine's ideal efficiency.