Why is it when it is 90 degrees or hotter my gas mileage go's up about 2-3 mpg.
I am about to change my oil so i expect to come up a little. bin getting 19-20
when it gets hot100 or moreit will go to 21-24. and it is better if i am driving in to the sun for a long trip.

got any ideas?
it's all stock 2007 4.7 flex fule

 

Gasoline is thinner when it's hotter out...

 

doesnt fuel injection compensate for all that? and keep it all kinda level flowing

 

You should get better mileage when it is cold out, the air is more dense...

 

If the air is denser, wouldn't it be harder to drive through?
So if the air is hotter and less dense it would be easier to drive through!!
[sm=badbadbad.gif]

 

that makes sense on a note, but overall thats wrong, bc of when the air is hotter, it doesnt cool your engine as efficiently. you do want cooler air. its like in nascar, the cars out front and cars on the edges are getting air, but the cars inside the pack arnt. thats why you see a lot of cars in the middle of the pack get on the outside and fall back, their engine is running hotter and so its producing less hp. that means you have to run at higher rpms to go the same speed, which means your using more gas, and your cars running hotter, and making less power

 

I wouldn't complain too much...I'm getting 16.0 to 16.8 mpg. Night Runner is kind of right. Ideally you want cold air (hence there are CAIs) which means there's more oxygen in a given volume. But (depending on design) you want a hot engine. Spraying gas into a hot engine will help vaporize it. Of course you don't want it so hot that you cook the block or so hot the fuel burns prematutely. No one has any fun when it goes off too quickly.

I just noticed you said flex fuel. I wonder what if any affect that has. What fuel are you using? Alcohol should burn cooler and not like hot temps.

 

ah flex fuel, i didnt see that. ive heard in many cases, they are getting the same or worse mpg

 

Only if running E85...

Regular gas they are the same... I read a thing on Yahoo! one day with a new Suburban, with regular gas it went like 400 some miles, and they ran it near bone dry, so there was no regular gas in there, then they filled it up some with E85, drove it around liek that, then let it get near empty again, and then filled it with E85, they went the same trip, and with E85, they went like 280 miles, but there was slightly more power to it, as the E85 is a higher octane than regular gas.