All owners of fuel-injected BMWs should check the main fuel filter (the one with the fuel pump) and replace it every ten thousand miles, not at the much longer intervals recommended by the factory.
The filter is so efficient that it soon becomes clogged.
First, there’s some missing, hard starting when hot, and lack of top end. Then comes difficulty going over 50 mph, then trouble getting to 50, then a top end of 20 mph. This can occur overnight or in the course of just one day’s driving.
Carry a BMW fuel filter with you. It’s a part unique to BMW (nothing else can be substituted) and the car will not run with it missing.
Cut an old one in half with a hacksaw and note the grundge trapped in it. You will need a 10mm wrench and two 17mm wrenches to change the filter.
As a general rule, try not to gas up while gas is being delivered at the station too much sediment gets stirred up. It will settle out in about ten minutes.
Remember that tanks are lower at many gas stations these days and the chances are greater that some sediment will get into your tank.