I gave up on car kits. I think the cabin noise in my car is too loud (could be that aftermarket non-resonated exhaust

) and the mic doesnt filter out noise as well as headsets.
But if you're driving in a luxury car that separates the outside environment from the cabin, then it would probably work well.
I would stay away from the Sony-Ericson HB-330 that I had (i think thats the model). I dont think its compatible.