The car's hdd is the central component of the system, which is why it's so important that the drive has sufficient storage capacity for the entire vehicle's data. As capacities continue to grow, we will see a shift from the multiple systems that exist in cars today (telemetry, navigation, entertainment, etc) to a single onboard hard disk drive that will serve as the repository for all of this information.
In a modern HDD, which is most likely what will be installed in the car stereo, you can see the spinning platters with their metallic coating, the motor hub with copper-colored stator coils surrounding it, and the actuator arm that moves the heads around the discs. These heads read and write binary code sequentially on the surface of the platters. The drives are non-volatile, meaning that they retain stored data even when powered off.
An HDD can be accessed by typing its name in the search bar of a computer program and then clicking on the drive icon. Once you click on the drive icon, a file browser will appear that allows you to select from any of the files, folders, or directories that are stored on your car's hard drive.
HDD manufacturers are getting much better at building discs that can withstand the bumps, jars, and other sonic assaults of driving while still maintaining high reliability. However, even the most reliable hard drives will eventually fail. The jiggle, bounce, and heat of a car's ride over 100,000 miles will likely wreak havoc on the drive, especially if you've been rear-ended at 40mph.
