Credit is due for an effective portrayal of a world of home-garage sportscars and street racing. The setting New Zealand, but I imagine street racing culture is similar elsewhere.
Cam and his friends appear to be regular, working-class people whose main passion is performance cars. They're not criminals, drifters, or deranged adrenaline junkies. With strict attention to detail and mundane concerns about the price of replacement parts, they like to soup up cars and drive them fast. From that standpoint this book is probably more realistic than the glamorized Fast & Furious movie series.
A lot of the car jargon (or perhaps New Zealand slang) went over my head. But I felt the book was doing what novels should do, which is to take us to another place to experience something we never would in our own lives.
That being said, it was all a bit too slice-of-life and light on plot. Cam coordinates a great big race around the middle of the book, and then the story runs out of gas. Structurally or from a developmental editing standpoint, it would have been better for the book to lead up to and end with the big race. Or at least create a more definable plot, which was the biggest omission of the book.
Instead, Shiftlight was more like a sequence of vignettes--some happy, some sad, somewhat disconnected.