So HST revealed their gray car yesterday.
I thought, "come on guys, get an imagination." McLaren, Mercedes and Virgin are all already using gray as their main colours - a full third of the cars on the grid will be gray.
I think each team must choose a unique colour scheme with up to two colours. Oldest teams get priority. Each team would then have to stick to that colour scheme, with minor changes allowed for sponsorship.
That way, each car is uniquely coloured, and the grid looks prettier.