BMW did quite a bit to differentiate the new 3 series from the old one, but arguably the biggest development in that department is the splitting of the model line. Because the new 3 Series is only the sedan and wagon. The coupe and cabrio are branching off as the 4 series
http://www.autoblog.com/2012/05/10/bmw-4-series-cabrio-caught-with-its-top-down/