[natickdan]

A couple of suggestions:

Amtrak:
They have a car service from the Orlando area to Washington D.C.

Carriers:
I looked in to this on Ebay.com and there are many. Just be careful to check credentials.

Personal Transport Services:

I've seen this service advertised in local papers and they offer to transport (drive) a vehicle to your destination. I don't know how cost effective this is, but I wouldn't not be comfortable with this choice. I'm a little anal about my car and, well, I have a wee bit of a trust issue, especially when it comes to someone else driving my car. Nonetheless, it's an option that may appeal to many.