One problem related to engine has been reported for the 2004 BMW X3. The most recently reported issues are listed below.
I have a 2004 330ci with a 6 spd transmission. This has happened in the past but this past weekend my car was in idle in traffic. My vehicle would do rough idling and the engine rpm would dip then surge eventually leading the car to lose engine power and die. This can be a safety concern when there is a possibly of someone rear ending you if the car just loses engine power. It's not a human problem but engine defect.