I'm looking for something that I can put on my driver's seat. I've got a bad back from an old car wreck (my right side is damaged from when I grabbed the gear shift when the idiot broadsided my engine going 70). It usually doesn't bother me on long road trips, but my gigging trips are another matter. I tend to drive for 1-2 hours there, play the cello for several hours and then drive back. I'm ok for the drive there and most of the playing, but the drive back is killing me. I would love to find something that I could plug in and heat up for that drive back. Any suggestions guys?