94 2door, M5OD manual tranny, 3:73s, 32BFGs
w/ 175,500 on the engine.
Tires run at 28/26psi front/rear summer and 32/30 winter
In town: 14-16 depending on how heavy my foot is
Trips at 34/32psi
Highway:
65-69mph @2100-2250rpms a/c off, windows down...17.5-17.9mpg
70-75mph @2300-2500rpms a/c off...17.2-17.5mpg
80+mph @2700-3000rpms ...15.2-16mgg
with a/c off and windows up I can get up to 18.4 if I stay between 65-69mph
65-69mph with a/c on...16.9-17.5
70-75mph with a/c on...16.9 is avg.
Pulling my 24' travel trailer 11-13mpg.. 4th gear @65mph
Keep in mind when traveling I usually carry an extra 600-700lbs of weight including cloths,food,tools,spare parts, jack, and other essentials in case of unforseen problems.
all in all, highway driving (which I do a lot of) is between 16-18mpg depending on speed, wind, and terrain. Most interstates the posted speed is 75mph once your out of city limits. This means I drive an avg speed of 80mph so my mpg is usually on the lower side of 15-16mpg. When trying to conserve money/gas or I have the time to spare I'll drive 70mph and usually stay right between 17-18mpgs.
I have tested many theories such as inflating tires, a/c, windows down, load, and other such things. All contribute to some degree but none more than 1mpg in difference.
The one that has the least effect seems to be tire inflation. When I go up to 39/37psi I see less than a .5 increase in mpg which IMO, does not outweigh the added tire wear, not to mention ride quality from over-inflation.
My next test (which I have been dying to try) is removal of my safari rack. This rack includes 4 daylighters at the front, a highlift jack, and my spare tire. I have a strong feeling that the added wind drag from this set-up effects by at least 2mpg.