Do you mean one of these.....
http://www.youtube.com/watch?v=2sBwAIqANxA
....if so I couldn't be doing with all the wires and aerial cluttering up the windscreen and dash. Have got a DAB in my 3 as an optional extra and sound quality and tuner stability excellent. Sound quality might be important in your coupe but no so much in a roadster. Clutter and wires outweigh the benefits i.m.o.