BMW 5 Series

[andrewlee]

What is the fin on the rear of the roof?

[uliolopar]

I always thought it was the radio antenna. . . .

[furrycheeky]

Its the antenna for the sat nav system.

[billryans]

it is a radio antenna. the sat nav reciever is built into the roof lining.

[mitch1340]

I have a 5-series and the radio antena is inside the rear window glass. I don't have sat - nav so I'm guessing that's what it might be.

[nwps]

Its the inbuilt telephone ariel.