Adjust bumper:

WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.

Ideal setting (dimension):

Transition

should be flush on left/right side.
5.5 mm (tolerance + 0.5/-1 mm)
1 mm (tolerance + 1.5/-0 mm)
5 mm (tolerance + 0.5/-1 mm)

Fig 1: Adjusting Bumper Dimension
Courtesy of BMW OF NORTH AMERICA, INC.

Loosen nut (1) from wheel housing and adjust bracket (2).

Fig 2: Adjusting Bracket

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: Adjustment at shock absorber is also possible with bumper installed if spare wheel is removed (remove spare wheel, refer to Owner's Handbook).

Unfasten left/right screws (1).

Fig 3: Locating Left/Right Screws

Courtesy of BMW OF NORTH AMERICA, INC.