The best I have ever got out of mine was 22.7 and that was with my drag quad in the back. It gets 19-20 very consistently on the highway at 70-75mph. I have really no proof of this, but it seems to get better when I have a quad in the bed, so I wonder if bed cover would yield the same results? On a day with no wind pulling my 6x12 v-nose trailer with 2 quads in it and one quad in the bed I get 14. But, in Kansas, a day with no wind isn't very common. My truck only see's 91 octane.

 

Oh yeah, I forgot, I use premium only. I promise you that 87 will get worse mpg. I also have a tonneau cover and a front leveling kit.

 

I noticed the sweet spot for my truck was between 60-65mph. If I started going over 70 it starts to drop. This is running 90 octane...highest we can get from a pump up here

 

more than that!

that was with the vvt stuff in it. with the ls9 cam. gas mileage sucks.

 

Lol, was just throwing a ballpark number out there =)

 

we have almost an identical setup and are getting very similar mpg results. maybe its the leveling kit and 33's that keep us from getting the numbers that others are or maybe we aren't inflating our results.

i recall seeing many threads of area47 getting great results with tuning...maybe you could help me out? ive got an autocal

 

I'm actually pretty satisfied with my mileage. Last summer, I drove 2300 miles one way without shutting the truck off (even while eating, fueling, rest stops, etc) because it was mid-July and my dogs were with us. The trip average was about 16mpg, and I really wasn't driving for mpgs on that trip.

 

I just did a 1200 mile trip with my 3.73 4x4, and couldn't get any better than 18.7 at any speed above 65. Once I hit 75, the mileage dropped into the high 17s. This was with a completely stock tune on 87 and 93. I didn't see a noticeable mileage difference between the two fuels. The only way 87 would hurt you, is if the PCM is pulling timing at cruise, from what it would run with high octane fuel.

 

were you running in higher temps or higher humidity? Just curious.

 

It does pull timing on 87; that's why we say it will lose mpg. Did you not read your fuel cap? The recommended fuel is 91+ because it was factory tuned on 91+.