Not recommended. Much of the user interface depends upon your ability to see the on-screen menus so you know what you're selecting.

If all you ever wanted to do was to hit next/previous track and adjust the volume, then sure, you could mount it in the trunk. You could use some sort of infrared repeater system or a variation of the steering wheel control interfaces to control it. It would work.

But why? One of the reasons that the Rio Car is such a great product is its ability to search for and select music out of your vast collection. This requires seeing the screen.

Do you want to mount it in the trunk because there's already a stereo in your dash and no room for the Rio Car? Dump the existing stereo. Trust me, you won't miss it.

The Rio Car isn't like a CD changer. It's a completely different way of listening to your music, and you're going to want it up there where you can get to it.

Now, if after reading the above, you're still serious about using it in the trunk, and you happen to have a spare PalmPilot, you can use Palm Empeg or Palantir to control certain aspects of the player from the Palm's screen. You would probably also need an infrared repeater system or some other way to remotely control the player itself. The player is not as full featured or as user-friendly this way, and these programs require some Linux knowledge to install and use correctly. For instance, Palantir requires that you have an infrared connection to the player, and it can only queue up tunes for playback, it can't remotely control all aspects of the player. But it's one possible solution if you have no other alternative.

There are also ways to use serial commands, VNC, or XML to remotely control the empeg from a computer. But if your problem is that you don't have space in your dash for the empeg, then you won't have space in your dash for a computer, either.