I always find the experiences of others in the arena useful. We all have different driving conditions, styles, volume of stuff/passengers, etc. With my 1990 240 AW70 sedan I averaged very similar in the 8 months per year I could get "summer blend" fuel but once winter blend hit, I dropped to about 17 mpg city part of this was surely longer idle times while I fully cleared the car and bit from from pure joy of doing 4-wheel power slides in the snow on the deserted roads into work at 5 AM.

My 940 NA AW70L Wagon drops to about 16 city but that is 100% my fault. I wring every last bit of performance out of the B230F as the heavier car really is taxing the limited horsepower. If I drove with the pace of traffic, it would be higher as I do manage to match or beat the highway performance of that old sedan (24-25 mpg at 70 mph...better if I drop down even 5 mph).

Back further, my 1979 B21f, BW55 wagon got more than 20 city and highway varied DRASTICALLY regarding cruising speed. It would do 75 mph all day long at about 23-24 mpg while dropping it to 60 mph could get me 26-27 mpg. My 1976 M40, B21F sedan could get me about 31 mpg on the highway at 60 mph.