Trying to remember a novel about a young man in treatment

Question

I read this novel c. 2010. The main character's name was Nathaniel. In the beginning of the book he was in a car accident, and I believe the driver (his grandfather?) was killed. Nathaniel ends up being placed in some sort of psychiatric care, where he discovers that the accident (through a concussion?) has unlocked a talent for math, or perhaps just given him synesthesia? I don't really remember what the main conflict of the story was. I do remember that near the end of the book he and some of his friends from the center are AWOL and one of them, a kid on crutches, climbs on top of a parked car and "conducts a symphony" of car horns with his crutches. I remember the last chapter ends with Nathaniel and his love interest finally sleeping together and he says that when she says his name it appears in the air in front of him (synesthesia). But in the epilogue they break up. I'm pretty sure the whole thing was told in the first person.

I don't remember it being a particularly good book, but it's bugging me that I can't remember what it was called and can't seem to find it.

(There's a scene I remember that might not be part of this particular novel where the main character spends some time in a sensory deprivation tank and does not score with the pretty girl he meets at the hippie hangout said tank is attached to.)

Answer 1

This is an excellent summary of The Beautiful Miscellaneous, a novel by Dominic Smith, first published in 2007.

The protagonist is named Nathan Nelson (rather than Nathaniel), and after a car crash in which his grandfather was killed, he begins to suffer from synaesthesia. The scene with a boy on crutches conducting a "symphony of car horns" occurs towards the end of the book. From a goodreads review:

Toby, Nathan’s blind musical prodigy best friend, jumps up (carefully, because he’s blind) onto the roof of Nathan’s car. They are stuck in a traffic jam, caused by Nathan’s car stalling due to old age, and are being assaulted by a barrage of horns and insults. Toby stands on the roof of the offending vehicle and with his cane (remember that he’s blind) he begins to conduct the bleating horns.

Nathan indeed spends some time in a sensory deprivation tank, trying to score with a pretty, hippie-chick called Amber while they are both high on marijuana. But although they seem to get along she just feeds him pumpkin seeds as they lie on grass looking up at the sky, and nothing more develops.