When I unscrew the filler cap there's a hissing sound which is either caused by a vacuum in the tank (and the air is rushing in) or pressure in the tank (air is rushing out). I can't tell which it is. Is this normal or do I have a blocked breather somewhere? :surprise: The car is performing...

Not sure what thread to post this on so General Discussion sounds like a good start. I have a '09 Type S and everytime I go to fill up and unscrew the fuel cap a lot of air rushs out. Is this normal ??? I wouldn't of thought that a lot of air in the fuel tank would be a good thing ?!?!?