I might have found a source that can actually get us the BMW pads, spec wise.. the size of the mat might still be a bit different but wattage and resistance values are the same.

Basically the pad is 50x27cm, 3 wire, 30watts, 10k resistance for the temperature sensor (this is what that BMW sensor is at also). $30.

They can also create a 50watts pad, however that would be slightly more, $40 for two pads. These pads are also with alloy wire and not carbon fiber inserts.

My question, are the BMW pads 50watts, each for the backrest and bottom? Or is it 50watts total combined between the two pads?

Also, I am unsure of this alloy wire vs. carbon fiber stuff how well it will work.