I think every car supports it... the connections are different for some of the manufactures and some cars give you more info than others..... but here is a link:http://www.obd-2.com/ The "Virtual Dashboard" could maybe work as a visual? These things are sweet. You can find out what the Check Engine light is on for (or at least what the trouble code is) and even reset it.

This link if for Windows, but it runs on Windows 3.1, so I assume the empeg wont have any trouble with a Linux version.