From Wikipedia

In 1993, the development programme for the E46 began under chief engineer Wolfgang Ziebart and head of R&D Wolfgang Reitzle. In late 1993, design work began under chief designer Chris Bangle and continued into 1995. In May 1995, the general exterior design of the E46 by Erik Goplen of DesignworksUSA was approved and as a result DesignworksUSA was contracted by BMW to work alongside BMW Group’s in-house design team to create the exterior body work for the 3 Series range in February 1996. The design team put an emphasis on improving aerodynamics and increasing the car’s aggressive stance. Design patents were filed in Germany on 16 July 1997 and in the US on 16 January 1998