Not a good idea unfortunately for at least 2 reasons, most other team supporters hate us pretty bad therefore giving them an excuse to damage you pride and joy, I used to have a sticker on Bulldogs logo on the back window of my car, I had 3 over a couple of years because hoons who dislike the team you support take great delight in tearing them off or scribbled foul absentives over them with a marker pen. Sad isn't it?
Even when I used to live in Sydney the same happened, there was no surprise to have people spit all over ones car when parked in the street or parking lot, even had someone urine on my car @ Baulkham Hills once only thankfully.
Some nasty people in this world.