I had a little stumbling the other day on the highway. No SES light, but I did pull a Peake code "81" - which is "lack of fuel".
Replaced the Fuel Filter today. Some have mentioned that BMW says the OEM filter is good to 100K. Uh, I beg to differ as is evident on mine.
With merely 51K miles on my M5, I removed the STOCK (date stamped) fuel filter and replaced it with a new one (HENGST). (p.s., guys this is a easy job!)
I did the ol' blow test which really took A LOT of pressure to get air flowing. Of course there is gas saturated in the filter, but I feel strongly this restriction was more than just normal saturated gas in the filter element. I broke out the hack saw and Dremel, and opened up the stock filter out of curiosity sake). I am fairly certain the filter is NOT supposed to be black. A mere rub with a paper towel showed some real crap!
Something else I noticed is the tweaking of the element. That can't be healthy and probably assisted in the restriction (one would assume).
-QUICK FUEL FILTER CHANGE:
1) Jack drivers side, support vehicle for safety
2) Remove plastic cover shield under the car
3) Relieve fuel pressure (A- press. reflief valve)
4) Unbolt (2) 10MM clamp bolts
5) Loosen filter at NUT end, 19mm wrench on the filter, 24mm wrench on square regulator
6) (B- other end of filter) push in white pressure clip, pull filter out
7) Install new filter ( with NEW copper crush washer) and by reverse of above (mark date on new filter)