Actually they build their cars much like we developers build web sites around a web framework. There's very few base models of cars (most shared by several manu

Actually they build their cars much like we developers build web sites around a web framework. There's very few base models of cars (most shared by several manufacturers) that get customized to look like a Saab, BMW or whatnot. The difference is mainly in looks and some parts, but the total solution is calculated once by joint projects between manufacturers, it not economical to build a car from scratch for just one manufacturer.