Venom watched the show as Spider-Man made short work of the bank robbers, he expected nothing less from the Spider. After each time a robber was webbed to a wall, Venom fired off a small glob of webbing to cover the robber's face and suffocate them. It was a glorious night, dealing out judgement and at the same time hoping his actions would show the public how evil Spider-Man truly was.
Venom decided that he should 'help' the spider out and swung low towards the car. As he passed by over the car reaching the bottom of his swing, he fired off a web line snagging the back of the car and tugged while rising. The back of the car rising with him threatening to flip. See, what a good samaritan Venom was! He was helping the Spider stop the runaway car.