trip computer weirdness

[Dan DiBiase]

Do the older cars NOT have 2 modes for MPG - instantaneous and average?  I have both - and the instantaneous can read as high as 200 mpg (after  which you get a '------') when decelerating or otherwise under minimal  load..... But I assume the 'miles to go' function runs off the average  MPG, which I believe recalcs every 15 miles or so. 
  
  Dan D
  '04 A4 1.8Tq MT-6
  Central NJ USA