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MPG - is this difference between the digital read out and my calculations normal?

My car has a digital reading of the average mpg. When compared to the real mpg which is calculated when I refill, the digital reading is higher.

This is not a surprise, since presumably the onboard computer takes no account of idling or aircon etc.

For my Make/Model, your 'real mpg' is over 100% of the manufacturer's figure - I wonder if this is because people are entering the digital figures rather than the manually calculated figures?

Is there any correlation between your Real MPG figures over 100% and cars which have onboard computers showing average MPG?

Asked on 8 November 2012 by physicalperfection

Answered by Honest John
Could be. Real mpg accepts meter figures or calculated figures. The whole point is that it is an average of all different types of use and all different means of measuring. My 320dED shows about 10% better on the meter than the calculated brim to brim figure. That's fairly typical. I've even seen 84mpg over 250 miles. But I enter the calculated figure.

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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