The fuels distributed by specialised oil companies contain so-called performance additives. When added to gasoline and diesel fuels, these chemical compounds modify the characteristics of these fuels to improve engine performance and longevity.

Modern, compact and sophisticated engines are especially sensitive to certain problems such as fouling, which reduces engine performance and longevity, increases fuel consumption and the emission of carbon dioxide and pollutants. High-quality fuels with additives are probably the most effective in countering the negative effects of fouling, notably thanks to the detergent additives they contain (see the following paragraph). A premium fuel with additives can be used for both curative and preventive purposes.