What is the biggest level jump for a Level 0 BOB?

[autofusion]

Most level 0 BOB's that complete an endurance race will get a huge level spike! Which endurance races will give you the best result?

 

[Snakebitten]

Been covered but if you have the Nurburgring 24hours unlocked you will jump from 0-36. Another 24 hours Nurb you get to 39. You what happens if you do another one