You can also use it through your car radio by setting it to use a frequency you can select yourself, in an unused area on the FM frequency band.
Garmin recommend the lower band as it should be less cluttered.
If you have an auxiliary input in the sound system in the vehicle you are using it in, the best way I have found is to plug the unit directly in from the headphone out jack on the unit to the auxiliary input of the sound system. Not only is there zero interference and a strong signal, but you can crank the volume up as much as you want with the sound system's controls. In some crowded metro areas like Vancouver, there just isn't any reliably clear FM stations with no interference overpowering the GPS.
One of the reasons I purchased a Nuvi 760 was because I am partially deaf and drive a noisy diesel 4WD, so there is now way I can hear route directions other than through the FM transmitter to the car radio
Keep in mind that if you do use the aux input on your car stereo, the volume level coming from Nuvi is lower comparing to the level that comes from the tuner or CD. You can, of course increase the volume on your stereo, but you will have to lower it back when you listen to CD or to radio.