When I go to a full service gas station and they twist off the cap the first thing they say is "how long you been driving on E". In the summer when I top off the tank and drive around in hot weather I can hear the hissing from the gas cap. I also get a gas dribble mark from where the gas has actually came out from the pressure. I have switched the cap and the fuel filter with no change in the pressure. But now that i have heard all these people say the same thing I wont even worry about it.