Your phone, more than likely, can transmit audio over Bluetooth. Many cars can receive these types of signals, but some can’t. You could use something that goes into your line-in jack that has to be recharged intermittently, but why not forgo having to worry about charging your adapter with this clever kit from Amber Logix. The actual Bluetooth device uses less than 1% of the power coming from your car’s DC adapter, allowing you to use the female USB hub coming out of the Bluetooth module to charge another device.
These adapters are available in red, white, and orange for your listening pleasure, and the kits are sold in packs of 2. So you could give one to your significant other as a brilliant birthday gift, or perhaps use the other one’s components for a different project. The possibilities are endless, as long as they involve USB power and/or car charging!
Or you may have to resort to other inferior options such as an FM transmitter or tape deck adapter. On a related note, the fact that cars didn’t come with line-in jacks as standard since the 1990s still seems ludicrous to me, but that’s an entirely different subject!