Automatic reset on MPG Readout

[98TXRed]

My average miles-per-gallon readout has reset itself twice in the last couple of months. It then builds up a history again so that the readout is accurate again (both the average miles-per-gallon readout and miles-to empty readout). Does anyone know why this would happen and what can be done to correct it?

 

[DRTH VTR]

I don't have my owner's manual with me, so I did not look this up. It seems to me that the average MPG is based on the last 20 gallons only. A change in the type of driving done is not averaged out by what was done last month.

Others- Is that correct?

 

[98TXRed]

Regardless of if the average is based on the last 20 miles, the last month, or the last year, what is happening is that it is actually zeroing out and starting over as if the car has never been driven. Very weird!