Hey guys. This may be a noob question, but when you're braking, do you waste gas?

 

If your engine is on your using gas. Slamming on the brakes is worse for MPG than slow stops however.

 

this is a very vague question. if you're asking about hypermiling, the trick is to brake as you're coming to a redlight but not stop completely as it is less efficient for the car to accelerate from a standstill than if you're already moving. but as long as your engine is on regardless if you're moving or not, the car is using gas. if that doesn't answer your question, you might want to elaborate

 

In effect yes, because you are converting kinetic energy into heat in the brakes when you stop and it takes energy to accelerate again. Hybrid cars use regenerative breaking to convert kinetic energy into electrical energy stored in a battery which is used to accelerate again. That's the main advantage of hybrid cars that they use regenerative breaking to reduce the energy lost in stopping and starting again.