There are three cars which have never been reported in the UCD:-
Buick - Special '62 (SEMA Gran Turismo Awards 2003)
HPA Motorsports - Stage II R32 (SEMA Gran Turismo Awards 2004)
Jaguar - XFR '10
All three are prize cars.
For more info read the USD thread
https://www.gtplanet.net/forum/showthread.php?t=134403