On the most basic level? DT was in a car with other people "hot boxing" the thing and doing 118. What? He didn't inhale? Maybe that's why they were doing 118mph! Had to get DT back to Eugene before he passed out from holding his breath.
It's also incredibly difficult to sleep in a car while "your buddies" are smoking pot in said automobile, I know, I've tried it. The only way it's humanly possible is if you've already been through the munchie and crash stages.:thumb: