What is the little "box" in the middle of the trunk?
 

Just learning about my newly purchased 2004 SL500. Have read much on this forum, but still do not know for sure what the little box on the outside in the middle of the trunk. My guess is a satellite radio antenna but not sure. Kind of wish it wasn,t there.

It is the SAT antenna.

It's the antenna for SIrius radio. The GPS antenna is in the front windshield.

Yes,that is exactly what I was talking about. I wasn't seeing the antenna on pictures of other SL's. The clear coat on mine had deteriorated so in the process of repainting it. Too bad it is there, don't like satellite radio anyway. Thanks for the info and pic.

I love Sirius radio, but I hate that puck. On my CLK, the rear trunk lid was fiberglass, and the antenna was located under the lid. I guess with the SL's being aluminum, it had to be outside the lid in order to get a signal. Of course this is only available on USA and Canadian models as that is the only place you can receive Sirius satellite radio.

The signal from he GPS satellites is very simple. It's basically a single stream that delivers a timestamp, and while you may have visibility to up to 9 satellites, you only need three to triangulate your position. The signals from the SiriusXM satellites carry much more data. There are over 200 audio channels, plus the do offer video and other data (traffic and weather). It needs a much stronger signal, thus the need for an unobstructed antenna. In fact, clouds, trees and buildings can weaken the signal to the point that the audio drops out briefly. To combat that, the data stream is buffered inside the radio. I have found that the "native Sirius" system that MBZ uses is very good at this and has minimal dropouts. My wife's Cadillac has a "native XM" radio and it's very bad about dropouts.