Ants in Car

Any suggestions for how to get rid of an ant infestation in a fleet of work cars? I have tried putting Raid on the tires to keep them away, sprayed Raid in the car, put ant bait in the vehicles and they keep returning. I have vacuumed out the cars so there are no crumbs/food source but they keep on returning. We have moved where we park the cars as we noticed an anthill nearby however they keep returning. Any suggestions?

terro is my typical response. put a little liquid down, bye bye.

AND
clean and remove all food residue that is attracting them in.

Local hardware store has ant traps that contain fairly benign and effective ingredients.

Lure them out by having a picnic nearby?

Ken’s right: You must have some food stuffs in those cars. Ants don’t bother visiting unless there’s food.