Well the 135i all came with sport suspension but I would probably say the iDrive system. No other *single* option would offer as much. What's nice is that they've bundled all options into basically two packages instead of the old a la carte.
The views and opinions expressed in this post are those of the author and do not necessarily reflect the official policy or position of Bimmerpost.
2014 CC R-Line DSG | 2010 S4 Sold | 2010 BMW 135i Retired | 2006 Lotus Exige Sold