FOR A SENSIBLE SOLUTION instead of wild guesses and mostly unproven solutions that will mar your paint:
Go to a pet shop or Bunnings and obtain pet deterrent & barrier crystals. Lay them around the perimeter of your car after hosing the surface (paving/concrete?) on which your car is parked thoroughly to wash away previous scents. For best results you need to damp them down and keep them damp with a small amount of water, taking care not to flush them away. After a few days that will be the end of the problem. You can use these to train your pets or other people animals to keep away from all sorts of places where you don't want them. After a while you don't need to refresh very often at all.
I have a cat and he doesn't sit on my cars at all.
CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV; Dashhawk; Prosport Boost Guage; JBR solid shift bushes; DBA 4000 Wiper-Slot front rotors; Hawk Ferro-Carbon HPS Street front brake pads (@ 69,000km); Sumitomo HTRZIII's in 225/45 x 18