Is it illegal to stick a car in Madou Studio?

Illegal.

Madou media originally spread obscene content, and Madou media posted on the car can report it.

It is generally not illegal to use police signs without blocking the license plate, which affects safe driving. Referring to Article 13 of the Regulations for the Implementation of the Road Traffic Safety Law of the People's Republic of China, motor vehicle number plates shall be hung at designated positions in front of and behind the vehicle to keep them clear and complete. Heavy and medium-sized trucks and their trailers, tractors and their trailers shall be painted with enlarged brand numbers at the rear of the carriage, and the words shall be correct and clear. Motor vehicle inspection signs and insurance signs shall be affixed to the upper right corner of the front window of the motor vehicle. Motor vehicle spraying, labeling or body advertising shall not affect safe driving.