Have you considered the 'parrot' car phone kit options? They come in a variety of options, basically each is a Bluetooth car kit, that bonds with your device,transfers the contacts, mutes your cars radio, and pumps telephone calls through the car speakers also, it is in every way a fully working car kit for the Xda range.
I am biased as I retail and install them, but every customer i do installs for, they absoultey love them, as they also bond with upto 5 devices so other phones can be used as well, ie a works phone,
Drop me a line if you need any help ok,
To view and buy all Xda Brodit cradles and proclips, visit my site www.dsldevelopments.com