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All down hill

An article in yesterdays paper that recommends, "Never coast in neutral; idling uses more fuel than running in gear on a closed throttle.” I don't understand how this can be. If you go down a hill for example with the car in gear but your foot off the accelerator the car is braked by the engine and gear box, whereas if you freewheel the car gains momentum and then you carry on for longer without using fuel. In both instances the car engine is still running but by coasting you use less fuel because freewheeling allows you to travel further. What is the most effective method of reducing fuel?

Asked on 25 January 2010 by AN, via email

Answered by Honest John
If you coast out of gear the engine has to idle to remain running and to do that it uses a little fuel. If you drive down an incline with your foot off the accelerator, the fuel supply is shut off, the drivetrain of the car turns the engine, and it uses no fuel at all.

Real MPG enables you to register the fuel economy you are actually getting against your make and model of car, its engine and type of transmission.

Every time you enter an average consumption figure against your car, the overall average automatically adjusts to reflect it.

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