In order to apply a layer of paint by spraying, as done in modern cars, it is necessary to distribute the colour pigments in a solution. During the drying process, the solvent "evaporates" and the cured paint is left behind. The solvents previously used caused harmful pollution because, although they easily volatilised, they formed toxic fumes.
Nowadays, for effective environmental relief, almost all automobile manufacturers use paints featuring water as a solvent. The previous solvent-based paints, the development of water-soluble is nowadays very advanced and there are no differences in terms of durability.