Dean tries to tell Cas, multiple times, that he's fine. That he just needs a couple minutes to recover. He's been whacked harder, after all, and by freaking angels. It's okay, he's okay, neither of them is dead and cracked ribs heal, so it's fine. If only Cas would listen.

He tolerates the passenger seat, but when he realizes where Cas is driving, he balks.

"Cas. Cas, c'mon no. We're not going there."