The guaranteed way to get an F-1 is to run the PD cup, winning at least 7 of the races. Then do the "save trick" at the end of race 9 and enter and leave the tenth race as many times as necessary to get the F094/s.
I would recommend using the Lotus 350 for the challenge or Viper on this one for a sure win of all races. (on Racing Slicks, of course).