On a trip this past weekend I logged 26mpg in my '93 245 w/ auto tranny and w/ my steamroller max performance tires. This was not a straight shot and included a bit of city driving, some stop and go, and a few stops. So a pure highway run would have been higher, since these deviations typically tank fuel mileage quickly.

26mpg may not sound so amazing, but in the past I had posted 21-22mpg. When I logged 21-22mpg the conditions were as follows:

-75+mph
-Roof carrier on car
-32-33 psi in tires
-AC ON
-Fresh copper plugs

When I achieved 26mpg the conditions were as follows:

-65mph
-NO roof carier
-IPD/TME springs (they lower car and are probably worth something in terms of mileage)
-33-34 psi in tires
-AC on 50% of the time
-Fresh Iridium plugs (for that special interstellar assist - Iridium is apparently not native to planet earth so it must be worth $5 per plug, right?
http://www.densoiridium.com/originofiridium.php )


It just goes to show how speed and a roof carrier can torpedo the gas mileage. That extra 4-5mpg is 60 miles per tank.