 Although power was generally less than existing Group C cars (around 650 bhp compared to around 750 bhp upwards) the new cars are considered to be among the quickest sportscars ever.However, the take up of these new regulations was slow and only a handful of Category 1 cars were ready for the 1991 season.Consequently, the FIA also allowed cars complying with pre-1991 Group C rules to contest the championship (as Group C Category 2 cars) during the one transitional year.