I'm considering purchasing a used Z4 M Roadster, and I'm wondering if there are any significant differences/changes/improvements between 2006 and 2008 that should sway which "vintage" I buy? Most of what I see available are 2006's, with a few 2007's, and even fewer 2008's.
Only main difference that I'm aware of is that in 2006 no Z4Ms had an AUX port. Besides that, it's the same throughout all years. 2007 is the easiest to find, because that's when most of the models were produced. Good luck! Best to read up here: http://www.zpost.com/forums/showthread.php?t=377102
2007 has TPMS in each wheel. The 2006 version has indirect measurement system (compared wheel rotations vs actual pressure).