Thread: 40 MPG?
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Old 06-02-2015, 01:10 PM   #39
extrashaky
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Quote:
Originally Posted by serialk11r View Post
IMy car did 38mpg at 65mph in cruise control coming back from the dealer, I got more because I press the clutch in when the road is downhill.
You actually got worse gas mileage by doing that. When you let the engine brake the car, the computer cuts off the fuel flow because no fuel is needed to turn the engine. The momentum of the car turns it. When you push in the clutch, the engine goes to idle, which burns fuel to keep the engine turning. Leaving it in gear going downhill therefore uses less fuel.

If you were driving an older car with a carburetor, it would have been the other way around.
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