Dodgy

I have it, I posted on here about my experiences in another Bluetooth+ thread. I ordered it so I could maintain a reliable data connection, data is much more sensitive to signal strength than voice or SMS. In the car on my driveway I get approximately 3 mbps (from Three) and with the phone in the bluetooth+ compartment it goes up to approx 13mbps, this was obviously repeated numerous time to see a pattern. It will be used to give passengers reliable wifi/internet connectivity on long journeys (to the Alps for instance).
 
If it's purely for voice calls, ime the signal inside the car is fine most of the time - all depends what network you're with and if you ever travel in sparsely populated areas.

Same on my car, they light up momentarily whilst the car does its start up/diagnostics routine. It's for the seatbelts.