I assume that it will work in a similar way to Hugo's own MP3 Mobile. The
unit will have power to it at all times, but will only power up the CPU,
harddisks, DSP etc when it needs to.
I imagine it will go like this:
1. You turn the ignition
2. Some hardware (not software) in the unit detects this
3. The CPU and hard drive are powered up
4. Linux boots from the flash RAM
5. The software reads the disk to find out where to resume from
6. The unit reads the next MP3 file in to RAM, spins down the hard disk and
starts playing

When you turn of the ignition the following probably happens:

1. You turn off ignition
2. Hardware in unit detects this and sends a signal to Linux (probably via
the serial interface)
3. Linux is given say 10 seconds to shutdown
4. As part of this shutdown the empeg software writes the resume position to
the hard disk
5. At the end of the 10 seconds whether Linux has shutdown properly or not
the unit removes power from the CPU and hard disk

This means to reset after a crash you just have to power the unit off.

I wouldn't be surprised to find our that the unit also makes use of the
watchdog module in Linux to reboot the system automatically if it has hung.

Number 330 in the queue...