I noticed that the Prius has somewhat more upright front seats; this is a big plus fort older folks who aren't so flexible. One way Honda gets good mpg is to keep the roofline/total height low. To do this they have to keep the front seats low, which requires that your legs stretch out more in front of you,not underneath you. In the Prius my lower leg-below the knee hands at pretty close to 90 degrees.In the HCH2 and our old Accord, my lower leg was at more like 60-70 degrees.This always stressed my back,and made it unsuitable for long trips.
Our Pilot on the other hand, has a nice comfortable seating position; we do the 1500 mile trip to Flagstaff,AZ stopping just for gas, food,and dog walks.It takes about 28 hours-total trip time.
I have the same problem with our 2001 Prizm; I'm only good for 30 minutes before my back starts yelling.
Thanks,
Charlie