Simon asked me to give you some more information on the filler cap solution.
The pictures show the original (old) tubes, the charcoal filter and the new tube, provided by MMC, that was fitted last week.
Filler caps are very complicated today, not only a tube and a cap like I had thought six months ago.
Probably the rule 'form follows function' was ignored by the designer.
Roderich

Sorry for the mess. I tried Flickr and it didn't work. Simon told me to use photobucket and it doesn't work. Obviously, I'm the problem.