A publicity vehicle is a vehicle equipped with outward-facing speakers that is typically used to play recorded messages at high volume while driving through residential areas. In many countries they are used by certain groups to spread political messages, such as to promote candidates during election campaigns. On other occasions, they are used as advertising and promotional advertisements. In Spain, messages from upholsterers, sharpeners and other trades broadcast to the population through mobile loudspeakers are typical.

These types of vehicles are also used by public security authorities in emergency situations such as evacuations to quickly transmit information to local populations. The use of loudspeaker vehicles to broadcast advertising is illegal in many jurisdictions. It is legal in Portugal and normally used during electoral campaigns by political parties. Also legal in Japan. For the legal situation in the United States see the cases Saia v. New York (1948)") and Kovacs v. Cooper (1949). In Bagé, Rio Grande Sul, Brazil, the sound level cannot exceed 65 decibels.[1]​.

In Spain, legality depends on the ordinance regulating outdoor advertising established in each province. Thus we find how in Granada this type of advertising is not legal unless it has authorization and in Madrid advertising through sound media is expressly prohibited.[2]​.