If that's the "instant" MPG, it means nothing. I had a trip computer in my 2000 Intrepid. Going downhill with no throttle on, it'd show 60 MPG. Conversely, uphill with power on, it might show 6 MPG.

It's the average MPG you have to look at, and my Intrepid would accurately reflect around 19-20 MPG overall. I'm not buying those numbers as your average.