I have a very large hairy dog who rides in the back with me all the time. So I bought fitted waterproof Prius seat covers for the back seat from our local Toyota dealer. When they came, I read the instructions and realized that it would be a major project to install them myself!!!! So I asked the dealer to do it...it was quite expensive (over $100 to install) and even they had difficulty with the folddown arm. I'm glad I have the waterproofing since T-bear periodically dumps his water dish all over; but if I'd realized I couldn't do the installation, I probably would have figured out something else.

In the front seat, I just picked up some sheepskin covers at Kragen and they work fine. They've been installed now for almost 2 years and 50,000 miles.