Party Jousting

I am not sure what the exact requirements are (i.e timing and number of vehicles to be destroyed). I tried destroying two vehicles at once several times (easy to do if two vehicles on the same team collide and get stuck) but it never unlocked the achievement.

What I finally did was start a game using one controller and all 8 possible buttons. For one team, I held down all 4 buttons for that team and they would eventually start turning in a very tight circle that basically allowed them to stay in place. Then, I used a car from the other team and skillfully started picking off the enemy cars. After about a minute or so of this method, the achievement unlocked.