Here is my Custom Event:
Track: Fairfield County
Car: used the main car with only performance upgrade
Deathmatch 2-20 MINS (see below), 23 opponents, AI Vehicle Sofa Car, Damage Realistic
HARD difficulty, Automatic, ABS off, TCS off, Stability off, difficulty Expert.
With 2 mins you can easy wreck 8-10+ cars and get 18-20K EXP points and 2.640 CR (FYI with 10 mins setup got 50 wreck and got 41k and same 2.640CR).
For LEVEL 25 you need 390k EXP points
For LEVEL 40 you need 990k EXP points
For LEVEL 45 you need 1.230k EXP points
For LEVEL 50 you need 1.530k EXP points