Create a traffic jam in an enclosed area, such as the Booth tunnel by blocking off both lanes with two vehicles. After the cars back up, steal some of them and squeeze them between the others so that there are three or four next to each other. Throw a grenade at the vehicles in front, then use a RPG to destroy the others.

Jackknife a bus on the Algonquin Bridge so that it is blocking all lanes. Once a bunch of vehicles have piled up, get on top of the bus, and use the RPG and grenades to destroy the vehicles and get the achievement.

Park ten vehicles at any gas station around the pumps. Get an RPG, and aim it at the gas pump. With two shots, all ten cars should explode.

Steal ten vehicles and park them next to each other, preferably in a smaller area, an inside corner, or the outside of a building so there is less of a chance the vehicles will push away when they explode. Then, use a weapon to make at least one vehicle explode. It should start a chain reaction and make the other vehicles explode.