"Fueling style" will definitely affect MPG figures by 10%+. You'll never get accurate mileage figures unless you top it off exactly the same way each time. That's why you see some people posting 40+MPG figures with aggressive style driving. Just can't possibly happen except for maybe a 190D 2.2 or 2.5.- and with conservative driving style.

The best I've ever gotten with my E300TD was 39.1 MPG driving at a rock-steady 60 mph for over 700 miles- easy acceleration, and no stops except for a couple toll booths.
My regular everyday semi aggressive driving style yields only about 26 mpg mixed city/highway driving average.

J.G.