Most times, if you are in the car and have keys in the ignition and you're drunk...you're busted. If you have possession of the keys too...you may still be busted.

Now...if you had NO KEYS in your possession at all and were just sleeping it off in your car, they should have no case against you whatsoever since you hadn't the capacity to start the car and drive off.

Last time I was in this situation when I was single and not in a condition to drive home, I put my keys somewhere that nobody could possibly find them (including the cops if they searched the car). The cops came and TRIED to bust me...and then I said I was just waiting until I sobered up and would have my "friend" bring me the keys when I did. I invited them to look around to prove I had no keys...and no capacity to start the car. Since I wasn't parked illegally, they had no choice but to let me go back to sleep.