Dean felt his jaw clench, not believing the man in front of them yet before looking to Sam "Go look for the car. You find anyone that even looks like they coulda taken it, kick their goddamned ass." His tone held something that more than read 'Don't argue this Sam, just go' and the message was received relatively loud and clear. There was hesitance before the younger Winchester left.

If anything happened out in the open, Dean would have witnesses that he was using self-defense. He turned to fully face Baby, looking him up and down in a very judging way. "So what the hell has you thinkin' you're my Baby?" This was where he figured out if this was a demon trick or some loony bin escapee.