I remember when I was about 18 in St. Louis, the State Police started putting "empty cars" on the highways as a deterrent. The problem was that after a few months people started shooting up the empty cars. The police pulled them for fear of some idiot shooting at an occupied one by mistake
There is a little town next to me that wanted to keep people at the speed limit
while going thru the downtown and they parked a cruiser along the main
street. Some days it had a live officer in it and some days it had a cardboard figure
all painted up like a real cop. It was very hard to tell which it was until you were right up on the car. Around here he was known as captain cardboard.
around 3/4 of the way down the page is the story