There's another thread about this, but my reading at fill up is usually 430 to 440. I think it just heeps a running calculation of fuel mileage and used the most recient figures when you fill up.
The average mpg reading on mine is higher than I get doing manual calculations. My dash reading sometimes hits 24 and for a full tank reads between 20 and 23 but hand calculationg gives me between 18 and 22, with a V8 and driving to get good mileage. I've acutally held 24mpg for quite a while and then had it suddenly drop 2 or 3mpg. My brother took it on a trip and got 16mpg, so I guess drivers make a difference. And I checked the range after he filled it up and it said 340 with just 10 miles on the fill up.
Since I't just me I wonder what things make more of a difference. My 4Runner is 2wd, V8, Michelin Crosses at 35psi and synthetic engine oil, and soon to get synthetic gear oil and trans fluid and 14.5k miles.
