Ok, here is a weird one for you. Ever since I installed my headers and Hypertech programmer, I have been averaging about 13 mpg, usually a little less when I have my foot in it. However, the last 3 tanks I have filled up, I got 14.9, then 15.4, then 15.7. I thought it was just a random difference at first, so that is why I let it go a few more tanks to make sure.

-I have not made any other modifications since I did the headers & programmer,
-power and performance has not changed as far as I can tell,
-my daily drive to work has not changed.

Only difference I can think is that the outside temps have dropped significantly in the last month now that winter is close. Maybe this is helping. I'm used to seeing mpg go down, not up. I'm not complaining, but anyone know what might be causing this? I am hoping it is not an idicator of some approaching problem.

Thanks.

 

Maybe ur special and buy really good gas....and yea i does seem reasonable that the cold air from outside is helping.

 

Ya, that reminds me, I also have been gasing at the same place I always do.

 

I know in this area the gas formula changes all the time due to EPA regs. Some is better than others. I have also discovered that some gas pumps are not real accurate. I went to the same pump three times in a row and was getting a calculated 18.5 mpg. I KNOW I never have and never will get that good. They finally figured it out and fixed it - mileage went right back to 12.9 on the next tank. I have gotten some 11mpg reads on fillups also - so I guess the bad pumps even out the good ones. Maybe this is your case......

 

I'd say there could be a couple of issues... one being the colder air. the colder the air, the more power you'll make which will help you to keep your foot out of it a little more. the other being the formula used in the gas, here in CA summer gas sucks and milage goes down. in the winter they change it and milage goes up, a little but not much although it is noticeable.