Adrian slept badly during the night. We had a late dinner yesterday so he was late to bed. Then he coughed himself awake several times during the night, and was extra confused because he was in Uppsala and not in his bed at home. By the evening he was pretty tired and fell asleep in the car.
He never naps otherwise. But tiredness + car + music is the combination that can still make him fall asleep during the day. Any music will do, even if it is rather energetic and loud.