Shooting in a car

I need to do some test shooting but I know people here have some insight.

Shooting a zero budget short film in a car on a black magic 4k. So everything’s already cramped. For some of the shots I was hoping to mount the camera on the windshield but I’m not sure what lens would give me a short enough focal length and a wide enough view to get two people

At this point I’m just thinking about shooting it on my cell phone because of the space constraints. If anyone has any insight I would be very welcome to it