Chain Reaction

"Destroy 10 vehicles in 10 seconds or less."

- In-game description

Chain Reaction is an achievement/trophy in Grand Theft Auto IV.

Acquisition
The easiest way to get this achievement/trophy is by blocking a busy road, such as Frankfort Avenue near Middle Park or gathering vehicles inside Westdyke Autos, then blowing up all of the cars which pile up using ideally a Rocket Launcher.

A very easy way to acquire:

With a motorcycle go to the Westdyke Autos, drive in and park near another motorcycle. In the showroom there are 8 motorcycles already parked. And you brought a 9th one. Go to the street and get a car. Drive into the showroom and push all motorcycles in one place with your car. If you ride a motorcycle, you give a 1-star wanted level. But they can be pushed freely. Park the car next to the 9 motorcycle, so there are 10 vehicles in a small place. Use a Grenade or an RPG to blow the whole pack.