Summary

This car will go on patrol on it's own. The geared motors, including the wheels are extremely cheap and available at the internet. He does not care to bumb into everything in his way.
At every bump he will change direction and starts all over again. No microprocessor or electronics. Just a battery and a switch. The switch flips over when he bumps. Make sure the motor direction is correct. If not, just flip the motor wires on the switch.
The bumper shields are connected by a sliding rod that activates the switch.
For the kids it is fun to chase him. He is hard to get.
https://youtu.be/ByrKC-k7RjM