Thnx Beppe for the quick answer, it was just what i needed, boolean air for the win

Hello there :)

is there a way to use a diffuse material with the matte option selected but without catching a shadow?
Cutting off all objects from view & giving a clean matte in other words?

car-render-masking-test.jpg

I want to matte all animated objects outside the cube-world ( car, people ...