2002 Sport/Prem 330i
I have the auto dimming rear view mirror and I really like it. It doesn't tilt like some other styles, it just dims itself, and reduces the glare from behind. It does a pretty good job of knowing when to dim and when not to.
You don't even have to think about it.
However, I don't know about any after market stuff.
In my opinion, it is nice to have, but I wouldn't go out and spend a couple of hundred bucks (or whatever) to put one on aftermarket.
Piece (yeah, that kind)
<span style='color:blue'>Piece (yeah that kind)
2002 330i Titanium Silver w/ Sport-Premium</span>