One of the most flexible, useful modern additions to car audio is the wireless communication technology Bluetooth. Most mobile phones, especially smart phones, are Bluetooth capable. They can use the wireless protocol to communicate with other devices and transmit data.
To use a car's built-in Bluetooth capabilities, simply enable your phone's Bluetooth radio and pair the device with the car. Take BMW's Bluetooth options, for example: Once you pair a phone with a BMW car, you can browse through your contacts with buttons on the steering wheel and use the car's receiver display to access the information on your phone. During a call, your voice will be picked up by a microphone in the car, and the voice on the other end will broadcast over the speaker system [source: BMW]. In states that have hands-free cell phone laws, built-in Bluetooth is an efficient way to stay in touch while your cell phone remains in your pocket.
Your car may not have come with the luxury of Bluetooth built into the audio system. If you're interested in Bluetooth, that's an easy problem to fix: Both Bluetooth and our next car audio component can be added to a car with a quality receiver, often called a head unit or stereo.