Well, let's back up a second: what is it about the car audio industry that you enjoy? In other words, what are you wanting to offer the industry?
I will recommend that you don't specialize in car audio. It is a poorly performing sector with very uneducated clientele.
As to how you get involved in the audio industry...
Continue your education. Audio is a simple application of physics, so knowledge in electronics, magnetics, mechanics, and thermal behaviour is critical. Ideally, it is very beneficial to have a background in DSP and you should be familiar with a variety of testing procedures for all ranges of audio equipment.
Take a look in VoiceCoil magazine and on the ALMA website (Audio Loudspeaker Manufacturers Association), where they list openings. AES, obviously, is also very useful. On the ALMA website, you occasionally see internships available as well (for example, Harmon usually has a summer internship).