Without a doubt the one I want and cannot buy is the Vector. Built back in the 1980's to compete in the IHPSC races, the Vector is easily the most streamlined and close to the ground. I believe the had 24 inch sew up tires in front and a 700c rear wheel. It had a lexan canopy and was constructed with 2 inch tubing. Apparently the huge clear canopy caused a few problems. It would cook you on warm days and fog up on cool days.
If you want to know about something really close in design stay tuned, I will be uploading a velomobile in the near future that could be a production version of this. It probably isn't, but it definitely has some of the same design cues.
Check out the link below for some more information on the Vector.