Apparently a 'lifetime' part, but Pelican recommend replacement every 60k to be on the safe side (sales pitch :wink: ). Their instructions are on the ///M pages but I'm guessing the tank set up is the same for the e85/6's?
https://www.pelicanparts.com/techarticles/BMW_Z4M/148-FUEL-Fuel_Filter_Replacement/148-FUEL-Fuel_Filter_Replacement.htm
Edit - Apparently NOT a tank out job, but requires draining and a lot of work! Anybody ever felt the need to do it?