On my 124 I have found that even a slight angle on the car (driver side down) when filling up is worth close to a gallon extra fill. I know this because my main filling station is like this, there is a concrete pad which transitions to asphalt causing a slight down angle. But since I use this place all the time I know my MPG results are quite consistent.

Rgds,
Chris W.
1995 E300D, 426K

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