What about if the protagonist is narrating the events in first person, stream of consciousness? Dialogue normalizes the intensity of the pace, since it's a mental diarrhea that is being spewed out. Also, possibly an occasional  chapter of an alternate point of view - the girlfriend - and maybe even one or two by the car buddy.  I think this might be the only way to keep this novel interesting, or at the very least alive.
The key is not to make the stream of consciousness too heavy, otherwise I'll lose readership. Proper context must be maintained and intensity should only increase during moments of high stress.
I'm going to give this some heavy thought. Sleep on it for a few nights, see if still sounds like a worthwhile approach next week. The main gain out of this though, is the ability to use the original characters and only redefine them by getting into their heads. Once inside there, there should be no limitations and pretty much anything goes.