One problem related to clutch has been reported for the 1998 BMW 540. The most recently reported issues are listed below.
I have drive standard transmissions for over 40 years, I have never had a clutch problem until a purchased a '95 540i (know for poorly designed clutches, particularly the pressure plate). I bought this new '98 with hopes the problem was solved, no such luck. If I had the failure on a major highway or crowded road I easily could have been in an accident the time for the clutch to stop working entirely was very short.