If I’m passed out in the back seat, they can arrest me? Arrest me for sleeping?
I wouldn’t doubt it. I know a guy who has a DUI conviction because he was showing somebody his car stereo at a party at his house. The car was in the driveway with another car parked behind him because he wasn’t planning on leaving the party, it was his house! The key was in the ignition and turned on, even though the car wasn’t running, so that was enough. Ironically, no neighbors had complained, the cop was just passing by and saw a bunch of people drinking from red plastic cups in the front yard. What a bunch of crap that was.
This happened in California in the mid 1990s while he was active military.