Just topped up WW reservoir, as I do so often, slightly overfilled with a run of excess fluid all down the inner wing top surface. Cloth not handy to stop it going everywhere but.... as I watched it run down the metal surface it arrived at a semi-circular plastic thingy about 1" wide and re-appeared on the drive under car. Someone really thought about it, brilliant design and engineering detail.

 

Their are many nifty things on the XJ like the soft close doors (which I'm still trying trying to teach my grandchildren don't have to be slammed , because the body has vents in the rear fenders that decompress it as if the windows are rolled down).