The South African Blaster system originally had gas tanks and could melt anybody on either side of the car, but the product was changed due to road safety fears in the event of a collision. They said it was an explosion hazard. I know that they were developing a CS gas version and in this California situation it would be ideal. If you run one of those arse-hats over with your car, you'll lose in court because he will say he was not one of the people denting your car. If you shoot one, you also lose because they will say when was your life in danger, especially since they appear to be unarmed (I saw one guy with a rod or stick). So I say CS gas them all.
If I wasn't worried about legal matters I would load up a high-capacity hopper on a paintball gun, have the gun at waist level and open up in 360 degree fire. If anyone got too lippy he might catch one in the face, tough luck if he loses an eye.