The highway sprawls out before him endless. This borrowed car can't eat up the miles fast enough he can't get far enough away. He's not running away, he can't run away, except he is. It's reckless, too fast and nowhere safe to go. You can't run from truth but he was giving it a good go.
Bobby and Sam would figure out he was gone soon and be looking for him. He can't bring himself to care. Driving like this pure focus on the feel of the car and road beneath her for the moment kept at bay memories of a broken angel, reservoirs and black goo. For the moment it fought off the crushing weight in his chest and he could breath. The radio turned up high drowning out his thoughts or rather a single repeated train of thought.
Castiel you child I love you, why didn't you listen to me? We could have fixed this.
I forgive you.