Hi all, while dismantling all the covers yesterday for access to apply Lanoguard, I found this block of foam rubber tucked in behind the wing on the UK passenger side. No sign of such a thing on the driver's side, and it's so firmly held up at the top that I guess you'd have to remove the wing panel to get it fully out.. always a possibility with an 11 yrs old car.

Seems like some kind of noise reducing thingy?

Anyhoo I sprayed behind it and pushed it back into place before reinstalling the wheel arch liner.

Usually this is fitted either for addressing vibration, noise, or protection of a component behind it.

Sometimes they are just "packed in", sometimes glued, sometimes held with a clip.

Lack of it on the other side is difficult to assess - it can be a deliberate design, for only the area needed (according to the principle of "maximum cost reduction" 😄), or, most likely, with time, the miles, or the mighty hand of someone that has worked on the car in its life, it has become lost ... 😄