One luxury the newest vehicles have is built-in Bluetooth, which is convenient for hands-free calling and streaming audio through the car's stereo system. For cars without it, there are portable devices that can enable that connection, in this case, without the need to actually hardwire anything.
Griffin BlueTrip Aux
Available at: Apple Store
The BlueTrip, conceptually speaking, was designed with the right idea in mind. A small Bluetooth receiver that is almost invisible when plugged into the 12-volt socket, coupled with a simple auxiliary cable with 3.5-mm jacks on either side. Plug one end into the module and the other to the car's AUX-In port, pair with a phone, and that's it.
But much like the reviews on the Apple Store's website, this product loses its way quickly. Call quality varies, though it's usually manageable. It's on the music side that the product falls apart, primarily because it muffles the bass for some inexplicable reason.
Tinkering with equalizer settings won't make much of a difference, and it certainly isn't an issue of one car or stereo system over another. Even high-quality digital music files fall prey to this problem. Unfortunately, it also doesn't charge your smartphone.
Belkin AirCast Bluetooth
Available at: Apple Store, Software City, BlueGear Wireless
The AirCast's module isn't all that big, but it also doesn't come with a clip, so it either has to be attached to the dash or centre console using the adhesive disc, or left loose somewhere.
Connectivity is the same deal as the others with an AUX-In cable going from the module to the car's input. Performance here is significantly better than the BlueTrip, and it helps that you can answer and end calls with the visible buttons on the module. An added bonus is the USB port for charging your phone.
For iPhone users, the AirCast is a bit of a letdown because it forces you to skip tracks manually through the phone itself, despite the arrows on the module. Holding down the phone button for two seconds initiates the phone's voice control (or Siri for iPhone 4S users), but you have to be precise or else it could unpair the phone.
XtremeMac InCharge Auto BT
Available at: The Source
The InCharge Auto BT functions much like Belkin's AirCast does, right down to the controls on the module. The one difference here is that only calls can be answered or ended, rather than also skipping between music tracks. It also comes equipped with an iPhone/iPod charging cable, though the USB port on the 12-volt plug can be used with any phone's charging cable.
Sound quality was quite good with the InCharge Auto BT. Calls were reasonably clear when echo effects weren't at play, music didn't sound muffled or distorted and the unit's design is small enough to lower its visibility, so as not to be intrusive.
On the flip side, managing your music requires manually dealing with your phone, which doesn't really promote safer driving. The main button on the unit can help a little, but it requires button sequences that you're not likely to use anyway.