Just joined the X5 tattoo club. Left cheek membership. Didn't burn through, thank goodness.
Since it must go into a state where decreased resistance at that point makes it pump more current, I'd like to see a heater element and grid from the driver seat and wiring diagram. It sounds like we could limit the current via thermistor. Even a simple one like this:
http://www.netrino.com/images/glossa...torCircuit.gif
Just set the thermistor at it's shut off temperature and set it at the edge of the seat where it gets hot on all of us. This would shut the seat off immediately if it got overheated and stop any burning through; saving the left cheek AND the $1,000 seat cusion.
Won't fix the element but as I stated in another thread, I like failsafes...... Plus as an EE I think about these things.