Although the microdrives are a neat technology, I don't think they'd fit into Empeg's plans. For pretty much the same reasons why Empeg doesn't have a CD-ROM capable model.
340 Megabytes isn't much storage by today's standards. The idea of the Empeg Car is that you should be able to store your entire CD collection on the thing. The bottom-of-the-line Empeg Car (4Gb) stores all of my favorites from my CD collection, but I need to add another drive soon so that it can hold everything. And my collection is a small one. For most folks, 340 megabytes is just a drop in the bucket.
That's why I laughed at the Diamond Rio. I have no idea why people are buying the things-- they have so little storage. Something like the Rio is useless to me. Even if the Rios had 340-meg microdrives, they would still be useless to me. The only reason I would want to go to the trouble of converting my CDs to MP3s is if I could get everything in one place. If I have to swap memory sticks, microdrives, or burned CD-ROMs, I might as well just cart the original CDs around with me, and not waste the time ripping them.
Now, a digital camera with a microdrive and an ethernet port, THAT would be proper application of the technology.