Parrot Minikit Neo
You may already yell at passengers and other road users, but it's time to learn a new vocabulary. Shout "Minikit" at this battery-powered gadget from Parrot (HK$949) and you have instant control over your smartphone. Follow that with the name of who you want to speak to, and the connection is instant. Incoming calls need only a brief "accept" or "reject" command. It uses Bluetooth to connect to up to two smartphones, so both the driver and a passenger can join in.
Belkin Aircast Auto
A good value step up from an FM transmitter, the Aircast Auto (HK$780) allows basic hands-free calling and plays music on a smartphone through the car stereo. Answering calls means clicking a button, and music requires a cable. Pairing over Bluetooth is quick, there's a USB slot to recharge a smartphone, and a separate microphone can be mounted anywhere on the dashboard for maximum voice sensitivity. It works with all brands of smartphones, but voice control is possible only with an iPhone.
Jabra Freeway Bluetooth Visor Speaker
This all-in-one device from Jabra (HK$1,198) includes three built-in speakers. Otherwise, it's similar to the Minikit, connecting to one or two smartphones via Bluetooth, and offering a full suite of voice controls. Designed to be clipped to the sun visor, the Freeway's three speakers make this all about top sound quality, but it's larger than most hands-free kits.