09 4dr X, 3.73 Gears, Auto, 35" BGF ATs.

I avgeraged 17.3 mpg on the highway traveling 11 hours to florida, figured it by hand. I was moving between 75-80 mph. I see the computer bump up to 18-20 if I move 55-65 with the wind, but have not done a whole tank like that to figure out how accurate that is. The computer does seem to reflect my hand calculations.

City driving I stay around 16 mpg, will dip under if its a constant stop-light day.

I used the procal to adjust my tires size. It was about a 2mpg loss from my stock 17 goodyears.

 

so i should lose to much thats all i wanted to know thanks guys

 

Curious - what gears are you running? Is that with a power tuner/programmer or have you recalibrated your speedo? I would love that kind of set up.

 

You are going to have inaccurate MPGs (not to mention speedometer) if you didn't correct for tire and gearing changes. Your auto transmission will also shift at less than optimal points. Need to get a Procal, Hypertech, or whatever programmer you choose and get the drive train corrected. I even had the dealer set the computer as close as he could so there wouldn't be any warranty issues ("sir, your tires are obviously oversized so your mileage is invalid, therefore we cannot honor your warranty.") Hasn't happened to me, but I've read where it has to others.

I don't care what anyone wants to believe, I can tell you the documented facts for my situation. I get about 19 MPG (+/- .5 MPG) round-trip highway miles to my place in the mountains - about 400 miles. Arizona isn't exactly flat either. That's with a 4" lift, winch, aftermarket bumpers, 35" BFG KM2s, 5.13 gears, etc. I use the Hypertech, but I doubt it helps in mileage much. I do use hypermiler techniques when I can.

I get a solid 12 MPG when I'm wheeling. Wish it were better, but considering speeds are well below 12 MPH for most of the trails, that's a loooooonnng day of wheeling for a tank of gas!

 

I get 17 mpg consistantly on the highway (doing around 70-80mph) and 15-17 backroads. I have 35inch tires with a 4.5 inch lift and 5.13 gears. However, I have reprogrammed using the Hypertech. Before I reprogrammed and told my rig the new tire and gear ratio, the onboard computer was showing about 12 mpg. You HAVE to reprogram when you change tire size and/or gear ratio...not only is the stock mileage, speedo and odometer calculation wrong, but the shift points will be wrong too, which will give you worse mileage due to inefficient shifting.

If anyone is getting 12 mpg highway, then they either drive very aggressively or they have something seriously wrong.

 

Well, I think this is pretty funny as my mileage claims are often disputed outright or quietly not believed. Doesn't seem to matter that I've made some effort to get them to where they are and also drive in a manner that promotes fuel mileage. I didn't buy the thing to be a Prius, but I also don't like going to the filling station any more than I need to.

 

That's what we averaged on our trip from San Diego, CA up to Niagara Rim and back. In addition to the info in the title we have the ProCal and reprogrammed for tires/gears. We put ~1,040 miles on it filling up or topping off 6 times. The average includes doing the trail runs up north plus the following freeway driving:
From SD to Niagara Rim Trail campground we had strong cross winds and spent most of the drive doing 70-75mph and driving up hill. *Our average was 13mpg.
From Niagara Rim Trail campground back to San Diego we averaged about 75-80mph and hit stop and go traffic in LA!
Average MPG on the computer for the trip was 14.5mpg.

*This is based on the OEM computer flashed using a proCal to our new specs. I have receipts from all the fill ups and can do a more accurate analysis since we started the trip on fumes and had to fill up immediately and came home with 1/4 tank left.

 

I'm curious what he is running anyways. . . .