Agasoline engine transforms approximately 34 percent of the fuel’s chemical energy into mechanical energy. if energy is conserved, what happens to the other 66 percent?

Wouldn't it be transformed into another form of energy, since it is an engine shouldn't there be heat and sound? I forgot the word for it but basically the 66% of energy is just wasted energy so you don't need it but it is still there I guess? Cause energy can't be created nor destroyed. I don't know much I only did physics to year 10. Hope that helps