Yes, TV stations even do bumper stickers.
I don't know when I acquired the WOLF sticker. Clearly, it was before the station moved to channel 56.
WYOU had its bumper sticker campaign prior to my 1990 arrival. I'm guessing the sticker campaign was mid to late 80's, just after a new company called "Diversified Communications" took over the operation. On the back was a "Play it Safe" pledge. In other words, you promised not to be an idiot behind the wheel. There was also a contest entry blank.
There were two ways to win. If your sticker was spotted, and your plate number read on the air, you had to call the station to claim a daily prize. There was also a grand prize drawing with the mailed in entry blank.
If memory serves, WYOU bumper stickers were all over the place. Viewers, on the other hand...