White cloth hanging from a car window: what does this informal road sign mean?

There are several reasons why a driver might use this visual aid. The most frequent are:

Mechanical failure: when the  vehicle has stopped on the shoulder due to a technical problem and the driver wants to signal their presence to avoid collisions or request assistance.
Medical emergency: the driver is trying to warn others that they are transporting a person who needs urgent attention.
Caravans and group trips: in funeral processions, religious pilgrimages, or group trips, the white cloth serves to identify  vehicles that are part of the same group.
Lack of fuel: in some cases, it is  used to indicate that the car has run out of gasoline or diesel.

One of the most frequent questions is whether this gesture gives the driver priority over other traffic. The answer is clear: no. Traffic laws establish that only official emergency vehicles have right of way, provided they are traveling with their lights and sirens activated.

These  vehicles include:

Ambulances,
police patrol
cars, fire trucks,
and traffic control vehicles are not considered  emergency vehicles. A private car with a white sheet does not automatically acquire this status. Therefore, it is not authorized to run red lights, exceed speed limits, or enter exclusive lanes. Although the situation may be real and distressing, traffic laws still apply to everyone.

If you encounter a vehicle with a white cloth sticking out of the window, the best course of action is to remain calm and proceed with caution. Some helpful recommendations are: