Terrible curse that can befall robots. Most modern day people consider were-cars part of ancient folklore and scoff at it as silly ideas. Some unfortunate robots have, however, realised that this myth has a factual core.
When a robot is hit by the curse, it won't be aware about it. Every midnight, when the internal chronometer reset, the were-car routine will be activated. Powerful algorithms cause the original program to be over-ridden and the were-car routine take complete control of the body. Advanced morphology programs, integrated in the were-car routine, cause the body to change into a transportation vehicle. The result looks almost like a normal hovercar, but the ancient origin of the were-car curse shine through. Rather than superconducting electromagnets, the propulsion is done through a chemical combustion inside the car, the resulting force is then tranfered to a collection of vulcanized rubber discs. Through friction with the ground forward motion is achieved. Ancient texts name these rubber discs "wheels".
Were-cars prowl the surrounding area at night, looking for innocent victims. When a robot is attacked by a were-car the virus is transfered through an optical link. Humans are usually just killed. Next morning the were-car program will have run it course, and the robot will have no memory of the events.
When a robot is hit by the were-car virus, it's only options is to find the origin of the virus and kill it, or commit suicide. Otherwise the killings will never stop. When the originator of the were-car virus is killed, it will transmit the uninstall command.
Usually were-car virii are written on purpose, but ancient readme files indicate that it can be a spontaneous error. Otherwise known as "illegal operations".
Rumour has it that the following robots have been were-cars: Bender Bending Rodriguez, Calculon, Project Satan, count Vladimir of Thermostadt, Thesp-o-mat, Acting Unit 0.8 and David Duchovny