Make sure you sit with your rear-end all the way back, pressed firmly against the back of the seat. These seats are not made to be lounged in. My dad is 6'4" 230lbs. When he sits in the passenger seat he slides his butt down into a kind of lounging position. His butt is probably 5 inches from the back of the seat; this is a disaster for this type of seat design. The front of the seat totally collapes and the spring compresses all the way to the bottomming out point. Unlike the new foam under foam under foam seats, the spring loaded seats have only one way to be sat in; butt all the way back. I can drive for hours, step out of my 300sd and feel loose and ache free. If I do the same with foam seats (2004 Lexus, 2004 MB C-class) my lower back, ass-bones and hips scream at me for about 30 seconds untill I stretch and walk. I love the spring seats.