Specs are from a BMW TSB regarding proper Closed-Circuit Current Measurement: SI B 61 08 00 General Electrical Systems.
"On vehicles equipped with BMW Assist, there are additional current fluctuations as high as 500ma that last for approximately 2 minutes. The fluctuations occur every 15 minutes for up to 14 hours after key off. This is considered normal operation of the TCU and should not be considered a fault. This also applies to 2005 TCUs that were installed into earlier production vehicles as replacement parts."
E9x; I grouped the 3 series chassis designation; E90, E91, E92, & E93.