The big issue here is WHERE CAN POWER BE APPLIED in the engine bay area or in the coupe in w140. I know that at least in my car there is not possible to go into neutral with the gear selector without power. It is locked. Regarding the key: This has happened once before and then it was released by pushing the radiobutton or central lock button. (my father did it and hen dont know which button it was). But this time there is no power. Also it would be very interesting if someone could explain how the vacuum locks are designed and why Mercedes chosed them before electrical. Thanks!