Weird Smell and Water Leak!

Had any passenger in the back that might have dropped something?

Perhaps they dropped it back then and now it's starting to whiff. Can't think of any pipes that go back that way apart from the rear washer piping maybe??

Does seem a bit strange. Odd question but what does it smell of?

Blimey. Not left a window down and had some $hitbag chuck something in?

Got me stumped as well.

Damp! In my old golf I had a hairline crack in the taillight, I thought nothing much of it and to be honest had more important things on my plate than forking out for a new light. Anyways, within a week or 2 of seeing the crack, I started noticing a funky smell coming from the car each time I entered it. Eventually after looking all over the car for dropped food or a spill I had a look in the boot and low and behold the thing was flooded! Rain water had came through the crack and collected in the spare wheel compartment. I had no idea fresh rain water could smell this bad after such a short time and not to mention the bacteria build up on the spare wheel. It sounds to me like you have the same problem 1st step is finding the cause of the leak and 2nd step is eliminating it! Good luck

I'm guessing this is your problem and the smell is screen wash - http://www.seatcupra.net/forums/showthread.php?t=256638