Basic specifications:
Compatibility : The cable should be compatible with iPhones that use a Lightning port. Make sure the cable is Apple-certified (MFi Certified) to ensure it works with all iOS updates.
The other end of the cable : It depends on the type of audio port in your car. If you have a 3.5mm AUX port in your car, the other end of the cable should be 3.5mm.
Audio Quality : The cable should provide high quality audio without any drops or distortion. Make sure the cable is made of high quality materials.
Length : The cable should be of suitable length for use in the car, usually the ideal length is between 1 to 2 meters.
Durability : Make sure the cable is designed to be durable and able to withstand daily use in the car, such as cables covered with a braided nylon layer.