How can I quickly select all faces surrounded by 4 vertices or 4 edges? Besides Rectangle Select or Brush select is there anything faster/easier?

I want to relax the vertices on the roof of a van without having to select all edgeloops and then unselect the parts I do not need or add "shortest distance" selections for each edge loop until I have the selection I need.

Is there something quicker/easier? Like just select the 4 outer vertices or edges and say "select inside"?
I should have just read the according Blender docs site:
https://docs.blender.org/manual/en/dev/modeling/meshes/selecting/advanced.html

Mode: Edit Mode –> Edge select mode
Menu: Select ‣ Select Loop Inner-Region

Does exactly what I want.