well,i dont know if it works in PAL version.In all endurance race,the f1s are always appear at the below position of the four prize cars.that method could controll you always get the car in one position.
First,choose you car you will use to run,save game,and SHUT DOWN your PS2.Turn it on again,go directly to the endurance you want to run WITHOUT DOING ANYTHING ELSE.get into Qualify ONCE(you neednt to complete it),then go race.After that you can get the prize car in the position of bottom(in endurance,you will get a F1)
This is "Q1 O0" in the method,means enter Qualify once,Option 0 time(dont enter)