W124 Gas consumption

[ncc.1701]

Dear All
I am interested in city / highway
Expected / Observed Gas consumption for the following W124 models:

1992 W124 300E M103 2.6 4D
1989 W124 300E M103 without first starting gear
1995 W124 E320 M104 4D

My personal observations:
(91 octane)
City / Highway
1) 9.5 / 8 ( going down to 7.6 for extremely long drives)
2)11.5 / 9.5
3)12.5 / 11.5 (highway seems in high range).

Also some Canadian Flavor:
Using Esso actually makes mileage worth - please confirm