Level 25 unlocks the Endurance races :-
Looking forward to 24 hours of Nordschleife much ?.
Thats unlocked at level 40 but at level 25 you can race 60 laps of Grand Valley Speedway.
2 races on extreme I can't yet do, one of which is basically an F1 race and I don't have the car yet.
The other is the poxy 10 laps of Daytona using a Nascar, as the ai cheats like an absolute bitch and shunts and spins you with monotonous regularity and you can never get far enough in front to avoid 3 or 4 cars basically bump drafting past you.
I think there's 8 different endurance races which I shall make a start on tomorrow.