[KrautBurner]

Originally Posted by Hersbird

I agree, I think it is more a result driven by want. You want it to do better at the higher speed so the testing never gives the lower speed a real chance at success. More speed takes more power, more power takes more fuel, it's just physics. At speeds under 45 with different gearing and such where aero doesn't have as big of an effect I can see it, but once the car is in it's highest gear whatever that just off idle rpm is will be it's highest economy. If there was some problem with the tune or motor, again possible, maybe you are overcoming a vacuum leak or rich idle condition. Tuned for economy and in perfect mechanical condition, top gear, just off idle.

with TALL gearing, slow speeds arent going to work
below 45 in 6th gear, my GTO is below idle
the car works alot less at 1900rpm

I've done the same 300 mile trip from Silverdale, Wa to Cresswell, Oregon over 50 times in the same car
I was averaging 27-28mpg trying to keep my speeds down in the 60-65mph range, and was able to achieve 32-33mpg on the trips I could run @75mph
I'd call that noticable