Enzo says that that winter was especially hard for him, although he's unsure if it was the stairs, his hip dysplasia catching up, or if he was just tired of being a dog. He says he longed to shed his dog body and spent his days watching people outside, unable to greet or interact with them but wishing he could.
Enzo equates his advancing age with not just physical decay, but also his weariness with being a dog at all. Note that he's not wishing to not be in pain; he's wishing to be able to truly interact with people.
Enzo says that looking back, his state of mind attracted the car to him. It's snowing in the evening as he and Denny walk home from Volunteer Park, and Enzo is unsettled by the snow. Denny allows Enzo to walk unleashed, and Enzo loses track of Denny momentarily, ending up on the opposite side of an empty street. Denny calls for him and Enzo starts across the street. Denny suddenly screams for Enzo to wait, and then a car, hushed by the snow, hits Enzo.
While the rain amplifies mistakes, according to Denny, here the snow hushes mistakes, although the consequences are seemingly worse. Enzo's belief that he attracted the car to him with his state of mind follows his belief in manifesting. He felt down and tired, and therefore attracted a situation that would make him feel that way even more.
Lying on the pavement, Enzo thinks of how stupid he is for wanting to become a man when he was just hit by a car. Denny tries to settle Enzo and speak with the driver, a shaken teenager. Denny asks the teenager to drive him and Enzo home. As Denny and Enzo sit in the back seat, Denny comforts Enzo and instructs the boy to drive.
Enzo sees being hit by the car as a failure of his soul to be human enough to avoid such a thing.