I'm a bit late to this thread too but as I was reading I was thinking that if you hadn't already purchased one, I was going to say not to bother as it doesn't really work when the car is moving. All my conversations go like this:
Them: "Are you on a handsfree kit?"
Me: "Yes, its a bluetooth car kit"
Them: "Can you hear what I'm saying"
Me: "Yes, its my bluetooth car kit, its not very good"
Them: "I can hardly hear a thing your saying"
Me: "Its my sh1tty Bluetooth Car kit!!!"
Them: "Pardon?"
Me: "I'll call you when I've stopped"
Them: "I can't tell what you're saying"
Me: " "