How do you beat large hordes?

As the title says, I'm looking for good ways to clear streets. I was on a scavenging hunt to get food and other supplies. The problem is that Zombies come from everywhere and start swarming me. I hop into cars (Burglar op) and run some of them over and switch car again when it starts to make problems. But they just won't stop coming. I also have guns and a good amount of ammunition, however I don't think that I have enough for a ever growing crowd.

What is your strategy to clear streets?