But I do have one. Be it an Alfa Romeo, an Audi, an VW Golf etc., the game doesn't let me race F-class-only challenges, stating that I "have no suitable car" (or however it goes).
It began happening after I installed some cars (namely Tool831's F430 Scuderia, Murciélago LP640, Zonda F, CCX, CCXR and Gallardo Superleggera) and sound mods (Reilsss's Enzo, MC12 and S7 and F430 Scuderia, Murciélago LP640, SLR and Zonda F from other people whose names I don't remember). I've also edited the names of the cars I've downloaded with TDU Modding Tools, I've installed the magic map and a no-traffic hack (yeah, I'm a damn cheater :p ).
I know it's a relatively big list, but does anybody have any idea where the problem might be?