High fuel consumption - error on computer? error on fuelsystem?

Probably 19 hwy is about right if there were any stops at gas stations, stop signs etc. If you get out on level road and reset the thing at 60 or 70, whatever you want to do, it will tell you what you are actually doing on the highway. But stop once or twice and you will see how dramatically just a few stops impact mileage ratings. I would guess that you pure h/w mileage is like 24-25 mpg, around town 15-18. I have had two vans and that is what they average. If you notice anything dramatically change, check out the O2 sensor, I had one go from 20 to 12 mpg overnight after mine got hit, but no check engine light came on. Changing it reversed it change. I find my computer routinely is a mile or two high on its estimate.