RIT Dyes that are available in the same aisle as detergent and clothing cleaners at Walmart.

It is permanent and fun...will not rub off..

Heat up water not quite boiling and pour in the amount of dye that you want...not much is needed for light color changes but use good discretion. Dunk the whole car in (I stick a thin dowel or rod through the side open windows so I can easily pull it out without dying my hands colors for weeks...The dye does not stick to chrome but It will tint the plastic windows...Be sure to watch for warping windows when in reallly hot water. Don't BOIL it lol...

Ps. this is a quick run down...ask me for more detailed instructions if needed.