Comments on: I coast in neutral when i am driving, does switching the car from N to D and back hurt the transmission???

By: owner_of_a_lonely_CAR

owner_of_a_lonely_CAR — Fri, 03 Jul 2009 23:04:59 +0000

First, you waste more energy to accelerate you car back up to speed then to keep it going at constant speed. So you are not saving gas by coasting, then accelerating again.

Second, coast is similar to getting your car towed. And anybody knows that towing your car can ruin your transmission. Even though the engine is still running at idle there may be lack of enough lubricants running through the system.

Third, this is considered unsafe. There’s also a possiblity that if you were to slam on your power brakes, you might not have enough reserve vacuum built up because you were coasting.

Lastly, if you are going down hill and you actually have your foot off the gas, modern engine actually knows that you are coasting and shuts off most of the fuel to the engine fuel injectors.
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By: Mountain Top

Mountain Top — Fri, 03 Jul 2009 22:37:59 +0000

Unless you are going downhill, constant speed on flat (or relatively level ground) will get you better mileage than coasting then accelerating back to speed. The reason is, unless you also turn off the engine, it is using fuel but that fuel is contributing nothing to your forward motion, while at a constant speed and throttle setting you are burning exactly the amount of fuel needed to overcome drag. Your max mileage under such conditions will probably occur in the 40-45 MPH range because air resistance becomes the largest drag on the car at higher speeds.

As to your actual question – you are not wearing anything out. The overrun clutches will take care of any rotation mismatches between the car and engine.

Beware turning off the engine though – you will loose your power steering and power brakes.
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By: thagame911@sbcglobal.net

thagame911@sbcglobal.net — Fri, 03 Jul 2009 21:54:59 +0000

on a stick you wanna coast when u come up to a stop and pop the clutch. saves wear and tear on brake pads. but dont do it at high speeds
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By: Aussie Bloke

Aussie Bloke — Fri, 03 Jul 2009 21:47:59 +0000

It will wear the clutches inside the transmission every time you shift into drive, especially if you shift back into drive at more than a walking speed (4-5 mph.) It also reduces braking efficiency, as well as the amount of vacuum available to the brake booster. Coasting is very dangerous, and should never be done. it doesn’t matter if you drive stick shift or automatic – NEVER COAST!

Good luck!
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Been there, done that…