2 questions about fuel mileage

[TexasPigHunter]

1) during the middle of July I headed to Colorado for some ATV riding. With all my gear and ATV my truck weighed in at 10450. I have a SCT with a 210KEM tune and 35inch mud tires. I averaged 17.5mpg for that entire 2400 mile trip, even in the high altitude and hills of Co. When I got back to Texas in the 110 degree heat and the truck was unlaoded I could only achieve 13mpg. What gives?

2) my truck averages 13mpg, the lie-o-meter says 22.9 (I wish). When my fuel light comes on with 50 miles to go it's assuming that I'm getting 22.9mpg, so I really only have 26 miles to go, right?

[smotrs]

How much stop and go have you been doing prior to the 13mpg reading? Long highway trips generate the best mpg readings. Soon as you get to stop and go it disappears.

The DTE is based on the last 500mi driven. So whatever the running average was for the last 500mi is what will determine the DTE. This could be a combination of both the 17.5 and/or the 13 or neither. Depends on how many miles you have put on the vehicle since you got back.

[TexasPigHunter]

I have made quite a few all highway trips after getting back, all of which have been unloaded and over 500 miles. My last trip this weekend was 140miles each way all
highway and got a whopping 12.2. My guess is the heat, but I don't know, and all of this is cruising at 70

[bigt2317]

Originally Posted by TexasPigHunter

I have made quite a few all highway trips after getting back, all of which have been unloaded and over 500 miles. My last trip this weekend was 140miles each way all
highway and got a whopping 12.2. My guess is the heat, but I don't know, and all of this is cruising at 70

I know heat affects MPG a lot due to the air being less dense, resulting in making the engine work that much harder to achieve MPG that cooler air would deliver. Not sure on %'s or anything but I'd say from 60* to 100+* would eat about at least 2 or 3 MPG probably closer to 5. I know my wives old ford focus would get 30mpg in the winter and only 25mpg in the hot Texas summer