Obviously they dont really want the cats either if they are outside cats...and who would want a sh!tbox in the corner of thier house?
I say if they are on your car, that they are fair "game", and if it was my car Id put a bb or a pellet in their ass! You may even try lighting firecrackers...you know like the whole pack...surely they wouldnt come back after that scare, and if so just repeat!
I personally hate cats! Im not a mean person...but the lil F'ers make me sick! Im totally allergic to them...so I have no use for the lil sh!t eaters!