Hey,
just took my new (..well, new to me)... 06 Grand Caravan on it's first little 2 hour road trip. figgered out how to reset the little automatic mpg display before I left...and did like mostly all feeway drivin...

..and it said it was averaging about 27/28 mpg!... Yeh!

(Ikno, I kno..I'm sure the city mpg is a lot less, but I'm still happy)

 

My 97 GC gets average 25.8 MPG highway (187K miles). The best I ever had was 27.2 (just last year), so your 27/28 is real. City is probably around 17/18, takes alot of gas for moving from a dead stop.