"World's Worst Car Wash" is an orchestral piece from the Season 6 soundtrack.
Charlie steers Desmond's car over a pier into the water. The car sinks; Desmond frees himself and, when he can't release Charlie's seat belt, he swims to the surface, exiting through his open driver's side window. Desmond dives back and goes to Charlie's door. Charlie wakes, and, staring at Desmond, raises his palm to the window. For a moment Desmond sees Charlie show his palm at the Looking Glass hatch with the words "NOT PENNYS BOAT" written on his palm. He looks again and the vision has passed. Desmond gets the door open and brings Charlie to the surface.