Thank you for your response, Paul. But it is not the back of the seat that is the problem. It is the bottom of the seat. I feel like I am sitting on steel, but my husband doesn't seem to have a problem with it. I can last about an hour in the car. By then, the pain is radiating upwards to my back. I have tried every position possible with the seats, with the help of a service technician at Lexus. He provided me with a possible explanation- he said that many car companies are making their seats firmer and more sporty. My old Lexus was, believe it or not, a 2003 ES and the seats were positively cushy. When I bought the car, I did test drive it, notice the firmer bottom seat, but I was not in the car long enough for it to become painful. Other than the seats, I LOVE my new car, but may have to trade it. Dilemma is, for what? It has been suggested (by the technician) that we drive the RX because, in his opinion, it has the most comfortable seats. I guess that will be my next step.