BMW 535 Forum : “this may be dumb...where is the button for the gas tank lid? manual is gone and...”

under the passenger seat by the door

did you check both glove compartments? or beside the seat?

if the other replies don't work try pressing down on the fuel door and releasing it will pop open I found this out with a 02 330i i bought took 3 guys and 35 min to figure out

No button to open the gas tank lid. As long your doors are open the lid will be open, doors locked the gas tank lid will be locked too.