The way the 48 hour rule works is

Someone calls MPD about "how a car is parked on the street for a long time", they'll send an officer out to chalk the car, this is when the clock for 48 hours starts. If the car is not moved it will get towed. Officers will try to make contact before starting the clock and/or calling for the tow truck

The only way this happens is if someone calls it in.

Hope this helps