Mine has worked well for many years. One Spring I counted 23 of them that entered over the Winter.
I also use dryer sheets but I've found droppings on them, so they didn't do the job.
Fresh Cab seems to work well for the inside of the car. I've never found any traces inside a car when using that. If you open the door and you can't smell it, then it's time to change it with a new one. It smells nice.
