When driving in any vehicle, there is a meter by your health that can build up if you destroy things like light posts, benches, mailboxes, etc. However, this has to be done in quick succession to keep it built up. Hitting 5 objects will get it to 2x, 5 more to 3x, until you reach 5x, which unlocks this achievement.
I found the best place to do this is on the bridge down the street from the police station that unlocks after chapter four. It's a fairly long bridge & the road carries on for a bit after the bridge as well. Just stay on the right sidewalk & take out every light post. They are frequent enough you should have no trouble keeping the multiplyer going & building up. Try not to make any sudden swerves or turns, as you don't want to lose the meter build up.