It is interesting to see the evolution of in-car entertainment. What was once considered just a simple way to have music in the car while you drive has changed tremendously over the last 40 years.
It started off with just the basic radio tuner with 2 front speakers in the 1950s and then gradually evolved to include the 8 track tape deck.

The 8 track tape deck then was phased out and replaced with the smaller, lighter and thinner cassette deck which were able to play back more songs.

The cassette deck was then phased out in the 1990s with the CD player which was a step up in audio clarity and quality. The CD player was always prone to skipping during the early days as the CD reader were sensitive to bumps and vibration. Car audio manufacturers fixed the problem with advanced laser reading technology whereby the CD player would read ahead by a few seconds and store the music in the memory and in the event the car hits a bump on the road the CD player will produce the music uninterrupted. Cars also came with 4 speakers to enhance sound production to enable all the occupants of the car to hear the music equally well.

In the mid 2000, DVD players were introduced to provide video playback and better quality audio. The DVD was also able to store more music. The regulations in many country forbid video playback when the car is in motion hence the video playback will be disabled. This frustrated a lot of car owners with DVD players and many overcame this problem by grounding the negative wire of the car audio system with the park brake wire. This enabled the video playback to appear on the LCD display.

Next came the GPS navigation system which was a handy tool for motorists since it was impossible to remember all the streets in any city. GPS navigation system provided turn by turn instructions to get to a destination. GPS system is not 100% fool proof however as many motorists who lacked common sense drove their cars into flooded streets or into bridges that were flooded over. This goes to show that the tool is only as good as the user. The GPS navigation system cannot be considered in-car entertainment but in many cases it is integrated into the car audio system.

With the impending music and video files being digitized, more and more people were moving away from DVD players and started using USB drives which were much smaller and were able to store multiple gigabytes of data. Literally thousands of songs could be stored on a small USB drive with no distortion and is not affected by bumps or vibrations.

Having one LCD monitor at this point didn't seem enough for large cars so head rest LCD monitors were introduced to provide rear seat entertainment. The head rest LCD monitors came with DVD players and video games embedded for ultimate rear seat entertainment. Some taller cars had roof mount monitors for rear seat entertainment.

Then came the Ipad and Iphone wave which saw car audio system coming with ipod connectors and head rest mounts for Ipads.

As technology progressed the in-car entertainment had to constantly evolve to match. This on going changes meant that more functions were integrated into the car audio system. Like the BMW, the in-car entertainment system was integrated with the car's diagnostics and computer control system. It is no longer just a stand alone system where it works independently of the car's other functions.