What's this on the top of my 408 fuel tank?

[dwomby]

It looks like it must be for fuel evaporation. The pipe leads up into the lefthand C pillar but I don't know what happens to it up there. My old XJ6 had a similar setup that went to a dead end pipe coil in the C pillar. It allowed vapour to rise, then theoretically condense and dribble back into the tank. Is that how this works too?

This fitting is not shown on the parts manuals for the 408-409-410. Is it from a later car?

Thanks

David