I think they stiffen up the seat on my Prius. Make sure you get the real leather ($299 one), not the full PVC one. I am going to order mine probably next month when my ebay buck comes out.

Shot at 2011-01-21

Shot at 2011-01-22
This is what it looked like stock
http://image.automobilemag.com/f/gre...r_interior.jpg