I got a non-clean P1 for the last WTC 900 round I had left for the Bonus Menu at Suzuka, and then I bought myself an Alfa Romeo TI V6 touring car from the LCD since I didn't have one in my collection yet. On a similar note, I checked out the Ferrari dealership, and even though it said I had acquired the F12berlinetta, none of the colors were marked off, so I bought one in Rosso Corsa. Sure enough, I go back to my garage to see if I had one previously. I did not, and I do recall selling the white one I had acquired as part of the Ferrari menu.
The next World Circuits race I plan to do next is the Japanese 4WD 600 race at Red Bull Ring, as that one I haven't gotten around to doing yet. I might also do the WTC 900 round at Trial Mountain, too, and as far as Bonus Menus go, all that's left for me is the X2014 Nations Cup.
EDIT: From the WTC 900 bonus menu, I won myself the first Lamborghini VGT of my collection, and it was even in the green color I would've bought it in. I had also redeemed the Nissan Motorsports extra menu, and won myself a nice 500k credits. The only remaining extra menus for me both involve buying cars from Brand Central, specifically the X2014 Standard and the Aston Martin Valkyrie. Between the two, they'll set me back a notable 7m credits, but I can wait indefinitely for them, especially since I plan to save my credits at the moment. Indeed, for the trophy involving the three legendary cars, the Ferrari 330 P4 is the last car I need to buy.