Upon further review, they do all fall into the same era class:
LMP Era (LMP) - Full fendered sportscars from 1994 through current which ran in FIA, IMSA, or SCCA sanctioned events. Any motors (22k limit), tires, driveline configuration, or chassis material may be used. Bodies must be injection molded or resin cast and not vacuum molded. Thunderslot brand RTR cars are NOT eligible for this class, but their driveline components (wheels, axles, gears, tires) and guide assembly may be used for tuning.
So yes, even though the class name has LMP in its title, lots of other cars are welcome to the party.