the mas files of any of the non dlc tracks should be openable, look for the assetsMAPs.mas. (Silverstone, Zandvoort etc) hmm, didnt see this was in the cars section. Same should apply to cars. I think even the dlc cars have the liveries unlocked
Silverstone: Advertisements_Alb.dds Zandvoort: Advertisements_Alb.dds thats the texture with the logo, but your topic is under the "car section"