My Insight has a cracked windshield so I took the 01 Prius to work. On the trip up I averaged 70.8 mpg for a distance of 515 miles. At a 157% of the EPA hwy estimate that is a better percentage than my 100+ mpg trips in the Insight.
In regards to comfort I perfer the Insight as I can strech out my legs and actually lock my knees. The seats were fine but a little more legroom would be nice.
I used a engine load of either 30-35% or 44-48%. The 30-35% engine load gave better fuel economy but would loose speed quickly on a incline. The 44% range would keep a pretty steady 75 mpg but would climb most hills without slowing below 50. Have fun, Rick

 

The Prius definately seems to do better at higher speeds. I'm still not sure that the 2004 Prius is more fuel efecient than the Prius I, but either way, I definately seem to be able to get the best MPG between 50 and 70 MPH.

It seems that under 30 the MPG is invariably low (in the 20s-30s) at best.