In the Rome 2 hour endurance race, you do not to a set amount of laps you race for 2hours, and the laps goes up each time you cross the finish line. Like on the Trial Mountain endurance race, I did 81 laps in my TVR Speed 12 in 2hours and 5 seconds.
All you do is race for the 2hours and the laps will count up each time you cross the finish line.