I read Car PC Hacks just a few days ago, I was at the library and i saw it sitting there in the shelving pile so i borrowed it. Like everyone said everything is pretty much on the forums already... The problem with books (especially books in tech fields) is they get outdated VERY quickly. People come up with new and simpler ways to do things and new hardware is always coming out.
It is pretty much the forums in simple book form. Still a good read.