Fire G

Okay, first off, to get the Revenge Racer you must have 100% of the game completed. Meaning you don't have to get any trophies. So if you don't have it by now it means your missing a couple stars.

To get the said trophy, go into any crash race in that location and take the mobile dinner or some other vehicle with a crashbreaker over 8. Now create a pile-up with you in the middle, or close to, when the crashbreaker starts, tap R2 with both hands so as to get a 100% or as close as possible. If your pile-up is over 24 cars, and your close to the middle you should get at least 24 cars to be hit by the crashbreaker.