easiest way is on the second chapter first level Ïsle of Plight"
it's a really small stage and only has 200 Peds. my advise is first kill all the Pedestrians. you need to kill them all!!! all 200 and then just reload this level finish the race or crush all the cars
Chapter 2: Level 1: Isle of Plight
1: kill 200 Pedastrians (peds)
2: Crash all 5 other cars
3: fihish all 8 laps
this will take you about 30 min total for all 3.