FurthurOnTheFly
Glamping Society
OK, this is weird, but the owners manual says to run 87 or higher octane in the truck, and the fuel door says that premium is "recommended". Having fun with it, I have now run 6 tanks; 3 87 and 3 91 and monitored them closely. Running 91 I have been averaging 16.7 MPG mixed driving (mostly highway though), and with 87 I have been averaging 18.2 MPG with the same mixed driving and there is no difference in engine performance. I think I'm going to stick with 87 as it is producing better results for less money. On a side note, the trip to Prescott I averaged 14.3 on a mixed tank of 87 and 91 and averaged 14.2 MPG. But, we were loaded with gear, driving up the hills, did about 40 or so miles in 4wd and drove from Chino Valley to the camp with the tires at 20psi.
Oh, and I have a bit of a heavy foot.
Its funny you mention this because I noticed the exact same thing today on the 4Runner! The last 3 tanks have been 91 and I've been getting about 16.9 per tank...this current tank was back to 87 and with less than a quarter left I'm still at 19.3!