I rode my Worksman reverse-trike on one of the charity rides here in town, did the 16-mile route on it (took 2 hours, btw). Driving it on a street was very informative. You are pretty much going to "take the lane" whether you want to or not. It wasn't a problem on the charity ride because there were a lot of other cyclists out, but is a consideration.

That Rhoads car with the upright position reminds me of two things. First, is Ford's Quadricycle. Secondly, when I was a kid, my G.I. Joe had this go-cart looking car that would fold up into a giant backpack (an amazingly stupid idea, now that I think of it, but was neat at the time!) But from what I read, the Rhoads cars are rather slow, and not well suited to riding in traffic. It would be neat for a bike trail, such as where I use my Worksman trike. Also, those Rhoads cars are not cheap- adult upright trikes are far far less.

http://www.youtube.com/watch?v=ewOLn9U-rrk