It is basing the 'Miles to empty' calculation based on the current mpg average.
Example: In this case my around town driven Trax.
My current average is 31.1 mpg......I filled last Saturday prior to a one hour highway drive to my hangar. My 'Miles to Empty' showed 387 miles (I remember this kind of crap).
When I arrived at the hangar, the 'Miles to Empty' now showed 435......after driving 58 miles.
It had been rising for the entire ride based on my much lower fuel usage at highway speeds.
Anyways, I don't think you are seeing anything abnormal.
Rob
Example: In this case my around town driven Trax.
My current average is 31.1 mpg......I filled last Saturday prior to a one hour highway drive to my hangar. My 'Miles to Empty' showed 387 miles (I remember this kind of crap).
When I arrived at the hangar, the 'Miles to Empty' now showed 435......after driving 58 miles.
It had been rising for the entire ride based on my much lower fuel usage at highway speeds.
Anyways, I don't think you are seeing anything abnormal.
Rob