[JimD]

My overall mpg is about 28. The gauge shows 28 but my spreadsheet from actual fillup data is a bit lower.

I normally get a bit more than 100 miles before getting to 3/4 tank, then about 100 miles before getting to 1/2 tank and maybe another 70 before getting to the 1/4 mark. Then I get the light at around 300 miles. On a trip, this goes up. If I put my foot in it too many times, it comes down. The gauge is thus not totally linear but is reasonable. It probably has something to do with the gas tank shape.