Yes, the "Rolling Thunder" kill event is by far the best way to get infected kills the fastest. I average 1300 kills each time I do the 2 minute event, here a a few important tips on how to get more kills out of each time doing the event.
When you start, pick a direction you want to drive. Being in the event causes large amounts of infected to be everywhere so you don't have to go in the direction of an infected zone.
Having the tank moving fast is the key. The more ground you cover, the more infected you kill. Keep the tank going forward, its far faster than reverse.
As you drive, keep the turret pointed back the entire time. You can't see what is in the direction that your tank is moving but you don't need to because you don't need to turn the whole tank and everything in front of you will get ran over or shot when you pass by it.
With the turret pointed behind you as you drive, you can still hit everything on the road and the hunters can't reach you. Hold down both RB and RT so both weapons will be fired as fast as they can reload. When shooting behind you, the blast from the tank shooting will make you go faster instead of slowing you down.
Last of all, not only hit the main road you are on with shells but put some down a few of the side streets as you pass them, this will give you a few extra hundred kills each time doing the event.