Thanks for adding that filter super handy
Another suggestion for the future... A page that lists the cars you own on one side, and the ones you don't on the other be very handy for trading with people.
A few more gaps for you
Mazda | Mazda6 Concept '01 | Level 0 | 39,978
Ford | GT LM Race Car | Level 21 | 2,497,000
Pagani | Zonda C12S 7.3 '02 | Level 18 | 999,645
Mercedes | 190E 2.5 - 16 Evolution II Touring Car '92 | Level 14 | 1,485,000 (Note doesn't mention AMG in the UCD)
Opel | Calibra Touring Car '94 | Level 14 | 1,484,655
Toyota | Corolla Levin GT-Apex (AE86) '83 | Level 0 | 15,010
Nissan | 350Z Concept LM Race Car | Level 20 | 988,630
Honda | Castrol Mugen NSX '00 | Level 17 | 746,726
Mines | Lancer Evolution VI '00 | Level 12 | 149,576
Mazda | RX-8 Concept (Type-I) '01 | Level 5 | 64,962
Nissan | C-West Razo Silvia '01 | Level 12 | 74,565
Honda | NSX-R Prototype LM Road Car | Level 14 | 488,729
Nismo | Fairlady Z Z-Tune (Z33) '03 | Level 12 | 149,599
Peugeot | 205 Turbo 16 Rally Car '85 | Level 13 | 1,964,550
Nissan | GT-R Concept (Tokyo Motor Show 2001) | Level 10 | 999,425
Chevrolet | Corvette C5-R (CS) '00 | Level 22 | 1,983,030
Acura | HSC Concept '04 | Level 8 | 749,423
Pagani | Zonda LM Race Car | Level 22 | 991,010
Peugeot | 206 Rally Car '99 | Level 11 | 294,272
Errors
Renault Sport | Lutecia Renault Sport Trophy Race Car (Doesn't mention V6 24V in UCD)