The toy car has a sort of wind-up motor that is actuated by pressing down on the policeman. When released, the stored energy would be used to drive the car for a few meters, while the policeman slowly returns to his original position.
Due to a broken tooth in the transmission gear, the car would only make a small jump, releasing all the stored energy with a grinding noise, getting the car nowhere.
This model replaces that gear (printed in Ultimaker Tough PLA red with Ultimaker Breakaway Support Filament) and still works after two years of repeated use.
See how it works after the repair (very short sequence):
The author hasn't provided the model origin yet.