You will get three sets of opinions (waste of time, invaluable, doesn't matter). I am in the waste of time camp personally, but if it feels good.....

In the meantime, read this link. Rather entertaining, I thought....

http://www.lumenique.com/Cars/cargeneral/nomodsp1.htm

__________________
2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue