The Nomad was a prize car in the Japanese GT3. For the US release the car was replaced as a prize but with the use of an Action Replay you could add the car to your garage. I think I have a US save with that car in it. PAL territories of course had the bad deal as the body of the car was removed from the game (as was also the case with the 6 F1 cars again due to licensing/copyright). PAL just got what was to become the FGT as their sole F1 car in GT3. All the other parts to the cars were still there so you could play with them provided you were somewhat creative with an Action Replay.
I have been waiting for that NOMAD to appear for weeks. I suspect that I missed it when doing a long event. I am on my third run through the UCD (I think) as the FGT just appeared again. No worries on money though as I have been doing the Extreme Euro Rome race (trying out more Euro cars) and have around 15 million waiting for the "right" cars to appear in the UCD! NOMAD plus C9 or XJR9 for preference!