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Does coasting downhill use more fuel than remaining in gear?

Some tell me that coasting downhill in neutral uses more fuel than remaining in gear. However, the MPG computer in my 1992 Corrado G60 says otherwise. Do the same rules apply to both new and older cars?

Asked on 16 June 2012 by BC, Woodbridge

Answered by Honest John
In modern cars the fuel supply is shut off entirely on lift-off, but when coasting the engine needs fuel to idle. Not a lot of difference, but enough to state that coasting uses more fuel than simply lifting off in gear. I can't tell you if the fuel shuts off in a supercharged Corrado but it's amazing that the fuel computer still works at all on a 20-year-old car.

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.

Real MPG
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