Had a plane get me a couple years ago in my A6. Trooper waiting up ahead to hear info on CB i'm sure. Had a detector on and not a peep. Trooper didn't need it. Some Viper and Corvette guys will have a CB/scanner in car not only to talk to each other, but also hear chatter on police radio. My thought (dream) has been to use a gps (rns-e) and be able to hack into the gps units of police/trooper sqads to show where they are, and put it on a screen with a warning. I'm sure every one of those cars has got to have a gps unit in it. Now wouldn't that be sweet.
For now you'll just have to look through the sunroof to check for planes. You solar guys are screwed.