The following post is from Pinnacle church in Amarillo, TX, a new church start that is going very well. We have never put out flyers in parking lots for two reasons.
People come to the malls for miles around.
Most of the cars would likely be outside our target area. You have to get permission to put flyers on cars at malls, and that permission may take time to get if you get it at all. By going to the neighborhood, you will cover less homes than mall cars, but you are strategically targeting the people you want to reach. There is no easy way to reach out. Your only other alternative is to do bulk mail which can cost as little as 6 cents each if you mail correctly.