Just took my Fit on a 500+ mile long trip, consisting of 99.9% highway, with lots of long up hills to climb. Averaged a solid 30mpg on my way there, and 28mpg on the way back - I admit, I was pushing the Fit nearly 80mph uphill and a bit past 90mph downhill
Not bad at all considering the small engine. I wasn't tired after the long drive, so it was a good testament to the confyness of the seats
I did however miss a center arm rest, so perhaps in 2007 I'll be adding it to the Fit. The center console I've added really helped out on the trip, holding my cd's and my EasyPass tag - it was very easy to discern the covers of the cd's at night, thanks to the leds I installed. The T1R intake I installed wasn't too bad on the long drive: the droning sound only comes on during hard acceleration, and it ceases completely once you reach cruising speed - it sounds just like stock cruising at 80mph. I'll make that same trip again for Christmas, so I'm looking forwards to the drive again