How to add an AUX input to an Audi A4?

I recently bought a used Audi A4 and realized it doesn't have an auxiliary input for my phone. I've researched online but can't seem to find a straightforward solution. Any suggestions?

You can either purchase a new head unit that has AUX input capabilities or use an FM transmitter. The head unit option will provide better sound quality, but requires more work and a higher budget. The FM transmitter is an easy and cheaper option, but may not provide the best sound quality.

One solution is to use a Bluetooth car kit, which will allow you to connect your phone wirelessly to your car's audio system. Just make sure to get one with good reviews and a reputable brand. You can also inquire about installing an AUX input at a car audio shop.