Have you tried the 9V shock mats?
No problem. There exist, no joke, little mats you can place on your car (or chair or counter, or whatever) that hook up to a 9V battery. Basically, when the cat steps on them, they get a mild electric shock. Repeat 2 or 3 times and the cat no longer jumps on the car. My family got one when my mom got a new car and my father, dutiful husband that he is, got sick of seeing little kitty prints on the shiny paint. My parents, being sensitive animal lovers, made sure to test the mat out on their firstborn before using it on the cat. (Quote:"We can make another one like you. It'll be much harder to find another cat like her.") Check it out: http://www.petsmart.com/global/product_detail.jsp?cm_ven=goo&cm_pla=unknown&cm_ite=Content_sku&ASSORTMENT%3C%3East_id=2534374302023689&FOLDER%3C%3Efolder_id=2534374302032911&PRODUCT%3C%3Eprd_id=845524441775467&bmUID=1131497497054
Does that program come with a 2lbs sack of instant concrete, directions to the nearest lake, and a burlap sack?
yeah, you're right. the car I used it on long time ago was a hard top and was parked outside. It was still fun as hell throwing those balloons. The cats caught on quick and started running whenver I opened my door. (This is the part where the bleeding hearts [or women] go, "Ah, that was mean")