Burnout CRASH!

In a rush hour event blow up the pizza truck and hope for the magnet power up. Let the cars keep coming to you and listen for the countdown. When it hits 2 trigger the crashbreaker. I got this on the very first rush hour of the game.

EDIT 6/26/12

See jacky rooster's comment for alternate way.

I done this on Windrush&1st pile up event.its the 1st section of the game 3rd one down.as you drive up to the 1st intersection,there will be a vehicle coming,hit this,an try an block the middle of the crossroads,so nothing else can get past.i only used 2 crashbreakers,an let the traffic crash away an build up the pile.Be aware the vehicles can blow up on there own,by other cars hitting them.time it right an with a bit of luck BOOM 20 vehicles or more.

you can also try the "Set Em Up,Knock Em Down " achiev at the same time.its score 30 million in a pile up,only firing your crashbreaker a maximum of twice.use the same method as above,but try an block the intersection by smashing into the 1st vehicle,an only using 1 crashbreaker.keep 1 for the end if you can.i did it this way an got 37 million.