I just rented a 2005 Prius for the second time, this time to compare it to my 2006 HCH. It got much better mileage, averaging 46.2 (computer) when my HCH would get around 39 (computer) on the same route, driven the same way (80
mph highway, which was 90% of the trip, and a small amount of city driving with moderate acceleration). The route just from the rental place to my apartment, all highway, yielded 40 mpg in the Prius and 33.3 in my HCH.
Plus most of the Prius driving was with A/C on accidentally, but it was at a low fan speed, and the tires were at 32 PSI versus 50 PSI on my HCH. However I still feel the HCH is the better car, for me at least, because the Prius' windshield's cowl (bottom) is higher, steering is springier, interior is cheaper, instruments much worse, engine is very loud, dashboard sucks and isn't even in front of you, stock stereo is horrible, etc. Basically its only advantages are the excellent mileage, quicker acceleration, and an electric mode that actually works. Also its turning radius is noticeably smaller.