It's generally prohibited to camp in the great outdoors in a few European countries like Germany (check out this related question). Speaking for latter, it's allowed to sleep in your car however.
So, let's say I drive my Lada up a German mountain and sleep in it. Am I allowed to do so?
Note: I mean to sleep in the bare car. Like laying on the back seats or even in the common driver's seat if that's comfortable enough.
Edit: Aravona added a good point. Of course we can consider that we are generally allowed to drive there (not a privately owned land etc.).
Bonus question: If yes, am I still if I transform it to a camping-device?