Just re-watched the Third Stage with Funimation's dub (they've did a good job imo, at least better than what I've expected), and I've been left with a deep impression about it once again.
That makes me think back to when I first heard of it.
I guess it was around 7 years ago or so (at least I'm sure that was before manga itself was finalized) at one of russkie NFS-themed sites; there were plenty of JDM-obsessed guys who also have been obvious Initial D fans (like one of them having a GIF of Takumi drifting as an avatar). Gotta admit, firstly I felt rather thrown off about the whole Initial D deal thanks to the impression these guys have made to me (wise thought: never judge the franchise by its fanbase). At first I was like: "Eh, it's probably some sort of wankery towards JDM riceboxes along the lines of FnF(3) where everybody goes "SUGOI KANSEI DORIFTO" n shiz".
Then, probably after suggestion AJ-Lethal has made, if memory serves me right (that has also been rather long ago), I've got myself to watch the First Stage.
There is no "WHOA" in this universe that could describe my first impression. (and no, nothing Crash Bandicoot or Oney ever said would fit)
One thing that I still find highly impressive about Initial D is the high quality of storyline. Despite Takumi being an obvious Marty Sue when it comes to racing, almost every character (mostly the 100% of main cast though) feels real and lively. They have well thought-out personalities, they have lives and concerns besides cars and racing (even Itsuki), and you get to see it really well there (until Fourth Stage, where racing and its aspects hog the most of spotlight, which is, while rather educational, somewhat upsetting when you compare last three stages to first three stages). Without of these details, it would be much more bland.
So yeah, Initial D isn't 100% about cars and racing, and that's exactly why it's a great watch/read.