To the right of the Ultor building (on the map) where you spawn in is a Torment Fraud that has a useful intersection not too far from the start point, just run down the street a little and you're there in a few seconds.
Sometimes the cars create a traffic jam and you can lob yourself with jump then
to land on the pile of cars and basically roll around on top of them till you get the achievement. That being said though the traffic jam pile-up is completely random and the cars all exploding is random as well so don't expect to get it in a few tries, it might take up to 20 minutes of tries depending on how lucky you are.
Lobbing yourself will take a little practice and not always work when you want it to but you want to run
then hit jump followed by
about 3/4 of a second after and you want to be a pretty decent distance away around 30-40 feet or so. If done right you won't cause a huge impact from jumping close-up or from landing from a high up fall so it's less likely the cars will all explode and if a bunch of cars are jammed together you can lightly bounce/roll on top of the cluster and get the achievement.
The Torment Fraud is easy difficulty so just hit start the second you get gold and select retry, it's much faster than letting the points tally and selecting to try again from the street.
It'll take quite a few tries to get because of the randomness involved but persistence will pay off eventually.