My DW and I just completed an around-Lake-Michigan trip (1135 miles) in 4 days. Spent more time than normal driving that distance because we took scenic (slow) roads when possible.

I have a moderately touchy back (both of us: age 64), and my DW is recovering from a recently ruptured disc in her spine. She does strengthening exercises at a Neuro-spine center.

Guess what. Neither of us had a problem with our backs from riding/driving the Prius. Hotel beds -- that's another story. Although this is clearly not a definitive test (other than for us), it was based on repetition over several days, and therefore is not an insignificant data point.

The best vehicle we've had for back comfort was a 2001 Honda Odyssey. The Prius is neither better, nor worse, than the Odyssey(for us personaly, of course), and it had an adjustable lumbar support. We towed a trailer thousands of miles w/the Odyssey, so our comparison is fair.

I vote thumbs up for the Prius seats!!

ZinFan