Anyone have any suggestions to get rid of white water marks from the rear door cards caused by the usual water ingress issues??

 

Vinegar on a microfibre

What have you tried already?

As Chris_VRS, after testing on an unseen part first.

 

You can use an APC at a high dilution ratio and mf/soft brush.

I haven't tried anything yet.

 

What is APC, excuse my lack of knowledge.

All Purpose Cleaner.