dan yeates said:
If you don't have bluetooth, I'd probably go for the Parrot to give you bluetooth too although it's a bit more expensive.
The Dice Mediabridge 1500 includes bluetooth as well. You can select artist, track, playlist, or podcast using the radio station buttons, and, like dan yeates said, the steering wheel controls work great to select the next song/artist/playlist, etc.
You may or may not need the DSP adapter, depending on 1) the year of your car, and 2) your audio setup, which you have to visibly inspect in the trunk. I didn't need the DSP adapter, even though I have DSP, due to my audio setup in the trunk. According to bavariansoundwerks:
If you have a 2003 Z4, you most definitely need the additional DSP adapter.
If you have a '04-'09 Z4, you MAY need the DSP adapter (see below)
What if I might need the additional DSP adapter?
We need to locate the factory CD Changer Connections to identify which set of cables are present. Head to our youtube channel (BavSound) and search for your vehicle's iPod Integration Kit install guide (example: Z4 iPod) to see the location of the factory CD Changer connections. There will be one of the three sets of connections present in your BMW which will determine whether you need a DSP adapter:
(3 pin male, 6 pin male) - You do not need the additional DSP adapter.
(3 pin male, round coaxial cable) - You need the additional DSP adapter.
(3 pin male, 6 pin male, round coaxial cable) - You probably don't need the additional DSP adapter. You may wish to order it just in case, but may have to return it.