Quote:
Originally Posted by The_Laird
You'll never get an accurate fuel consumption figure if you use "roughly" and "estimated" values. The only way to do it is to zero the miles before the trip when you fill the tank. Then keep filling the tank and setting the miles to zero, noting the miles each time. And the end of the trip, fill up and note the miles. I've been doing this on every tankful for years (I know I need to get out more!).
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That's exactly what I did. Filled the tank, zeroed the miles.
Then kept receipts of every fill up. Then VCDS'ed the litres remaining at the end of the trip. As per my first post.
The only error in the calculation, as I already said, is that we cant measure precisely the litres remaining when VCDS measuring block reads 0 litrs, but we know some fuel remains because when I filled the tank I only managed to put 87l back in. (I was not willing to fill the tank to full after the trip just to get a more accurate measure how many were left)
The problem arises is that VCDS will carry on reading 0l even if you use some of those 7l below zero.
So the error in my calculation is assuming that there are another 7litres below zero when VCDS reads 4l remaining.
Even this margin of error +/- 7l is not enough to account for my previous best mileage, which was 581 miles with VCDS reading 1 litre remaining.
But those were different roads than the trip to France, that could explain some of the difference.