Will do

An update.

I took a road trip and while the Avg MPG calculations seem to be very close to the actual MPG, the "range" calculations continue to be mysterious. I got 27.6 MPG on the computer and 27.4 actual.

When the tank is filled the range says 340 - 345, but as you drive it changes. As you accumulate miles on the tank of gas the combination of miles traveled and the remaining range climb to well over 425 which makes me ask what data the computer is using to calculate range. For example, the computer should use two factors to calculate range (number of gallons times avg MPG) one of which is a constant and the other is being calculated by the very same computer.

I haven't disconnected the battery yet because I was told that it could cause issues such as having to have the throttle body cleaned.

Computer seems to be adjusting range based on overall MPG. If hwy driving then the MPG increases and so does range, if city then range will decrease.

The computer does not measure fuel flow or have any way to measure fuel temp to determine density. It is just an approximation.

You might research the issue of disconnecting the battery. The throttle may need to relearn what is normal driving. If having a stereo/navigation system the unit may loose all preset data and for the Nav system may require the installation DVD to be installed to get it to work again.

I think that is probably the issue but the math just doesn't make sense especially since it continues to say 340 range after I just got 425 miles on the last two tanks and didn't even see the low fule light. Even allowing for a reserve it would have to be basing range calculations on 19-20 MPG which simply isn't feasible.

The avg MPG when I got the car was 26.5 but who knows if that was one tank or 20,000 miles?

The good news is that the car is getting good MPG........it just doesn't know it:-)