Was stationary in dense traffic, all waiting for a local bridge to open. We had been waiting for 10 or so minutes. Had braked and stopped close to car in front, car in Auto Hold. All of a sudden, my car accelerated quickly into stationary car in front, twice I believe, before I was able to brake and turn car off. I do not know why this happened or whether there were any warnings. Affected my car, car in front of me, and car in front of them. No one hurt, my car front rather damaged, perhaps $12,000+, car in front damaged front and rear. We were able to drive away, but my car not safe to drive. Is currently parked and waiting to be towed once collision shop space is available. I have not taken to dealer to test as is not safe to drive. No one has inspected in person yet.