I had a car raio fitted recently at one of the largest places doing this. A Sony radio was duly fitted but it wouldn't work on key position one. I.E you can only have the radio on with the ignition sitched on. I as told all car radios ar like that now but it could be live wired but that would run the battery down all he time. I was told to sit with the ignition on to listen to the radio...is that a ood idea? I don't think so. I have contacted Mercedes and Sony who both reckon a radio should work in key position one. Of course the clock on he set dosen't keep time either for obvious reasons. The DAB aerial has been randomly stuck on he windscreen and looks a mess and the reception ain't great with intereference on some stations. I have complained big time and await with interest their response.