In this class some cars have DRS and others don't. Is this correct or an error? It would seem to be that this would create some inequalities or is there some BoP? Anyway, the cars are fun to drive.
It was like that in real life, as far as I know. Some of the cars that weren't specifically designed for this series (Ginetta and Ligier) never had DRS, and the rules of the series allowed for DRS so that's why the Brazilian prototypes (Sigma and MetalMoro) were designed with this in mind. Same with the 1st generation of these cars. As far as I remember the BoP isn't that bad anyway, since the Ginetta and Ligier have other advantages over the duration of a race, IIRC.