Board Thread:Game Discussion/@comment-28169398-20180706072412/@comment-31433854-20180706165114

MoisesGabby wrote: "We're aware of an issue with the Porsche 962C and Jaguar XJR-9 being incorrectly required for the Group C 1991 Motorsports series"

I'm reading that as they were not supposed to be there at all, and they will remove them. It could mean just as plainly that the Mazda/Merc need to be added to tiers 2 & 12.