Are you sure most car manufacturers compete in F1, the correct answer should be most car manufacturers do not compete in F1. F1 is a distraction and money burner.
There are currently No Japanese or Korean car manufacturer in 2010 F1, GM, Ford and Chrysler are also not into F1. Tata is not into F1. Fiat, Maserati, Lamboghini are not into F1 too. Only a few car makers are in F1.