This has been annoying me.... fresh wash/wax, after one day the trunk is filthy.

Is it something with the aerodynamics that pool air/kick up debris behind the trunk? Right now I’m running a roof and trunk lip.

Is there anything that can help with this?

 

It's the roof lip. It's preventing air over the top from making the turn over the rear window which would blow that debris off. The lip is probably forming an eddy that takes dirt in the air and reverses it so it drops on the trunk lid. Viewed from the left side of the car, it's a slow clockwise flow. Same eddy forms behind the cab of pick-ups.

https://ecomodder.com/blog/wp-conten.../10/CFD91.jpeg

 

It's certainly a thing, OP. A very noticeable and annoying thing. In addition to being the first body panel that gets dirty, it's also very susceptible to rail dust, so once you get it clean down to the clear coat (clay the trunk), you have to keep the trunk waxed more often than the rest of the car.

As I write that and think about it... the trunk face sure is a good candidate for ceramic coating.

 

Interesting, figured it was a dead zone. I'm referring to the back of the car itself (not the top of the trunk) but I don't think I noticed this until I put on the trunk lip.

 

Ceramic coating isn't a bad idea either. I don't have a problem washing my car every few days, I was just wondering if this happens to other folks too.

Maybe adding a diffuser might help, who knows.