The scented stuff is a combination of spearmint and pepermint
oil. I've used it in the garden shed and the mice still come in. I have placed bags of it under the hood of the tractor, Cobra, and all of the other cars just in case it does work. I also have two "Rat Zappers". One in the basement and one in the shed. Unfortunately, at least in the case of the mice in the basement, they figured out how to get around the contact plate that electrocutes them. The snap traps have worked the best, especially the plastic ones. The newer wooden ones aren't sensitive enough. The mice eat all of the peanut butter and the trap doesn't spring. The plastic ones are a lot more sensitive and successful.
I also hunt down snakes in my neighbor's yards and transplant them into our garden and around the shed for added security. So far no damage to any of the vehicles.