I enjoyed buying so many passenger cars that they started to clip into the engine, haha. I think if you decided to spend more time working on this after the jam I'd suggest you have the camera follow the car at a wide angle and allow you to move back and forth down the cars with the arrow keys, and have a little minimap showing where on the track you are. It'll make the zombies feel a little more immediate, and make it easier to place turrets lol.