Quote:

Quote:

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yes you are correct it is 10% out... i.e at 30mpg... it will read 27mph.



But which one is out... or are they both out?



The lower digital reading is the accurate one. Speedometers are allowwed to over-read by up to 10% but can't under-read at all. In practice, manufacturers set them to over-read by the full amount so that there's no chance that they might under-read.
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