Was cleaning the car earlier and noticed a build up of crud on rear inside wheel arches, around the edge of the wheel arch. Anyone whos owned an 90's BMW will be familiar with rust rot around the wheel arch edges, caused by the same type of build up.  Given how thin the sheet metal is on these cars I'd say it's a case of not if, but when.

 

I'll be powerhousing in there and making sure to clear it all out.

@Steviedakota

please add pictures

 

and maybe join to

https://www.briskoda.net/forums/topic/477247-rust-oh-my-rust/

 

Noticed one of the stone chips on my roof has started to rust...car must know it's about to go back!

Just noticed I've got a couple of rusting stone chips on the roof and one on the bonnet. Any advice for treating them and stopping them getting any worse? Thanks

You could use something like, but not limited to, Aquasteel. 
give the bottle a good shake, and apply to the stone chip using a toothpick. Allow 24hrs and apply a touch up to the area using a fresh tooth pick. Let the paint harden and sink in and apply another coat using the same method.