Here's a rather long discussion of the topic -
http://www.myturbodiesel.com/1000q/engine-break-in.htm.
The most salient advice in the article is, "My suggestion is to follow the owner's manual written by the people who made your car."
Look in the index to your owner's manual to find break-in procedures.
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'14 328d, '13 M3 ZCP, '12 535i, '11 335d, '09 Z4 DINAN Stage II, '05 330i ZHP, '05 M3 ZCP, '02 M3, '91 328i, '90 535i, '88 528e, '88 M5, '87 M6, '95 Z3, 95 M3, '93 M5, '87 325e, '89 535i, '86 635i, '73 Bavaria.