Why braking hard will cause gas wasted?

Question

"The Environmental Protection Agency estimates that accelerating rapidly and braking hard can reduce your car's fuel efficiency by as much as five percent."

Accelerating rapidly will cost a lot of gas, that makes sense, but how does braking hard cause the same effect on gas? Shouldn't it be saving gas instead, since there is a cut on gas burning?

Answer 1

Braking hard wastes alot of gas!!! Think about it, if your car is moving and you take your foot off of the gas, it would keep moving because it has momentum. If you brake then you lose that momentum and you have to use the gas to get started back up again. Try this: Next time you see a red light ahead of you, take your foot off of the gas and coast to the light, whats the point of hurrying up to get there and having to stop and wait

Answer 2

i think they mean what is the point of speeding up when you're going to brake anyway. i don't think they mean the braking itself contributes to wasting gas. like why speed up to slow down suddenly when you can just look ahead and cruise up the light without stepping more on the gas at all.

Answer 3

Lets say you are traveling with enough speed to travel 200 feet. You travel 80 feet and then slam on the brakes.

You waste gas because you used enough gas to travel 200 feet but you stopped at 80 feet.

Answer 4

You are not the only one who wondered about this. I thought that I had heard them wrong, so when I read your question I looked into it.

I found this in an article-the link is below...

"When you're driving down the street, and you see a light red light or stop sign up ahead, you should lay off the gas sooner rather than later.

There's no point in keeping your foot on the gas until just before you reach the intersection. Let off the pedal sooner and give your engine a rest as you coast to the stop while braking gently. As an added benefit, your brake pads will last longer, too."

So I guess this makes sense...over the course of a day that would add up to several minutes where you would normally have your foot on the pedal burning gas.

Answer 5

It takes a lot of gas to brake hard so thats why it wastes a lot of gas.

Answer 6

hard breaking at a stop light means you have to accelerate again to get back to speed. ALL acceleration uses more gas than maintaining a steady  speed.  So it's an indirect effect.  There may be a slight direct effect as well since hard breaking means your average RPM's prior to breaking will be higher than if you coasted or breaked more slowly but it's likely far less significant than the other reason.