For the average mileage calculation that appears in the odometer screen does anyone know what resets it? Seems that it self-resets at 1,000 miles. Is this correct?
I reset mine by accident and didn't want that to happen since I wanted an average MPG of all miles. And I think I did that by accident by holding down the trip button when on that screen.
On the large screen with the Nav and Radio there is an Eco App which allows you to create a bar graph of your MPG for any interval you want. I create a new "bar" each time I get a tank of gas. As such, I can see a bar graph that shows something like my last 5 tanks. The MPG for the most recent "bar" (which for me is for my most recent tank), shows up on the Odometer as the one reading that is independent of your trip odometer MPGs.
Relying on the car's trip meters to record your mpg: 1. You're getting the "rose tinted glasses" report. The consensus with 4th gen is displayed mpg is about 5% optimistic? 2. All it takes is a 12 volt battery disconnect, or an accidental push of the wrong button on the dash, and it's toast. If you want to retain an accurate lifetime mileage: start and maintain a spreadsheet log. For safety, use the odometer readings, not trip meters; the latter are too easy to reset. If someone borrows the car and gasses up without recording the odo, as long as you can get the gas receipt from them, you can lump it in with the next fill up.