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After reading the original question again, I thought I should make a new response. My car is: a coupe, with the A4 transmission, Z-51 with 3.42 gears.
First let me say that my Instant MPG only goes up to 70 MPG on deceleration. I thought I saw someone say theirs went up to 99 MPG but that isn't the case for me.
On a level road going 80 MPH, my instant MPG reads in the 22 to 24 MPG range. Of course this changes all the time with the slightest movement of the gas pedal or the slightest incline or decline of the road. I use the instant MPG reading as reference only to make adjustments to my driving at a given point in time. The actual Average MPG reading is far more useful to me when it comes to knowing what the car is really doing with gas mileage.