Alot of you probally already know this. I did a fuel octane test. I usually run 89 in my truck witch gives me around 300 or a little more miles to a tank. Well I put in 91 and yeild 333.9, so what roughly 33-34 more miles out of the tank. Yes filled up with the same amount (gallons) each time.
TRX 4 Package 3.92 LSD QC. Just thought this was interesting. Most of my driving is city so it would not benefit me in the long run to continue useing 91.

 

i was filling up with regular and getting about 15.5 mpg on the highway. i did 87 octane for a trip (about 160-180 miles), got 18.1 when i got there, 18.4 when i got home. speed limit the whole way, didnt really pass anyone, a/c off