daroon,

It does display the average mileage on a couple of the screens. There are two of the simplified energy flow screens. The first one (right after the blank screen with only the time and outside temperature at the top) with the bar graph displays instantaneous mileage. If you keep switching the displays (I don't remember the exact order), another energy flow screen comes up with just digits where the bar graph is on the other screen. This is the average mileage since the last refuel.

There's also another screen with the number of miles you've traveled at the bottom and the average mileage just above it. I believe that this is the one that has the instructions to the left of the numbers saying to press and hold the display button to reset it (Yep, it is - see below). I've reset mine after each fill up, but I'm not sure that I need to as there is another screen that shows you the mileage since the last fill up. [Note: After re-reading the Owner's Manual, this one is more of a trip totaller. It keeps averaging until you reset it.] I suppose that you could just leave this one alone and track the average mileage over the life of the vehicle.

The Prior Mileage graph is automatically updated each time that you fill up and shows the last five readings.

Here's a picture that I just found of the average mileage screen.



Here's the After Refuel Mileage and Range screen.



Here's the Prior Mileage screen.



And, finally, here's a picture that I found of the standard MFD version of the Energy Flow display. The engine is off in this shot, but would display directly above the battery.



I hope that this helps.