I have logged about 12,500 miles since my purchase last fall. I reset the unit when I purchased it. When I look at the Pro Driver III readouts I see all activity for the entire period 12,500 miles. I averaged 7.19 miles to the gallon over the entire 12,500 mile period. Now as you know this includes idle times as well which can represent a good portion of the total. When I look at the Pro Driver while running down the road It reads out around 6.5 MPG at 70MPH while towing on Economy transmission mode, the rest is combo of idle hours I guess. The Pro Driver III is a great tool.