Friend of mine went to sleep in his car at a bar, it was like 10pm, he had a few drinks and he decided that he'd sleep in his car untill he's sober...he was hoping to leave at like 2 or 3am. He started walking to his car and a cop stopped him said he'd better not get in a car. He told the cop he was just going to sleep in his car and cop said in California if your in posession of your car keys and within 15 feet of your car you can be arrested for a DUI. So the key's under the tire thing would really work. But then again the cop may just been an ass and lied...one reason I don't like cops is that they lie alot, I wish there was a law saying cops had to always tell the truth.