mk1 players will often thump on powerdown...

Dearing said here that it only happens on his mk1 with 2.0b3, and not 1.3

...your player definitely thinks it's in car? (check for a fader menu)

Yep, I the fader menu is there. I also see my "car" boot logo when in the car.

If there is anything else I can check, I would love to help...

Tom