What's the worst that could happen?
It should come as no surprise that this all started as a joke. Swiss mechanic Andras Birrer dressed up a Hyundai i40 in police colors and lights for an ad in his local Sursee newspaper, which jokingly claimed to offer the car as a rental to deter break ins for anyone going away on vacation. The ad got such a massive response that Birrer decided to actually offer the service. Weirdly, this isn't illegal. It is only illegal to drive the car, so it is delivered on a truck and must remain stationary.
Actual police have been skeptical about its effectiveness, although it would be difficult to prove whether it is working. Of course, the downside is that a police car that remains stationary for too long might soon become a beacon for thieves. Not only might they have a go at breaking into the house where it is parked, but also the car itself. In that scenario, there would be a cop car on the loose which the police didn't immediately know was missing. The potential problems with this are limited only by the criminal's imagination.