Most people use bluetooth receivers in tehri cars for listeing to audio. Even if you have a 10 year old car, you can put in a bluetooth receiver (what kind depends on whether your car has a single-DIN or double -DIn slot). Even if your car doesn't have a slot, products like  Audiovox MediaBridge, can be plugged in to enable bluetooth connectivity. Some bluetooth upgrades can be plugged in via the Aux-in jack.

The best bluetooth car stereo receiver: Pioneer MVH-X370BT (no extra fetaures such as CD player and high-end radio options, but great bluetooth compatibility)
The second best bluetooth car stereo receiver: Pioneer DEH-X6700BT (same as Pioneer MVH-X370BT but with a CD player, so a bit more cost)
The best upgrade for bluetooth car stereo receiver: Kenwood Excelon KDC-X998 HD Radio or SiriusXM compatibility and/or plan on adding a bunch of extra speakers and subwoofers.(expensive, HD Radio or SiriusXM compatibility, flexible so you can add  extra speakers and subwoofers.)