Fuel additives are chemicals added to the vehicle's tank to improve fuel quality and protect the engine. They can have several functions, such as increasing the octane number of gasoline, improving the lubrication of the injection system, reducing corrosion and cleaning impurities accumulated in the engine. Some additives can also improve fuel economy and reduce pollutant emissions. It is important to choose additives compatible with the type of fuel used by the vehicle and follow the manufacturer's recommendations to obtain the best results.