Or can they only be accessed from the your game? I'm asking because I am planning a big mod with many color options.
The fuel tank size, with the default being 75% of it (which can be changed anytime from the Tuning menu in Beam)
It won't export colors but there is an easy work around. You will need a special file known as info.json. I actually posted a blank info file with tons of colors. Just search "info". Good luck!