In a tech savvy world built on code and the interwebs, basically everything is programmable, including the songs on your iPod. And by programmable, we mean that everything digital can be composed of what we know and expect, but sometimes, it can also contain something... more.
This is mostly due to the massive switch from analog signals to digital signals. Analog signals can be converted or parsed into a digital bitstream from which a programmer can route or control which vector to manipulate. An example includes most modern vehicle stereos, which contain an ADC – Analog-to-Digital – to equalizer connection which converts analog signal to digital. From there, the signal is returned through a Digital-to-Analog Converter or DAC for short; rinse and repeat. The theory is that somewhere along the way code can parse the digital content. The odd part is that it's totally legit and "legal" on pirated music.
To say that a virus could be coded onto pirated music and then transferred to a vehicle's infotainment system, while quit plausible, is theoretically pointless unless the information from a random person's car is valuable enough to take the time to code such a monster. Not to mention that it's almost impossible to be incognito while attempting this feat while on the fly. When sending a digital signal over an analog connection, a driver would hear a series of beeps indicating the conversion. Since the driver would have to be playing his stereo, a hijacking would be an obvious give away every time. In the end however, no hacker would have the drive to code a program that would be destined to fail. And that's where the Reddit thread below goes. Check it out for a quick laugh.