Eso no he llegado a intentarlo, sin embargo, si creas un png sin más, debería aparecer, es extraño...
Thank you @ghiboz , I'll wait for the update with the asset. About the livery, I've tried copying one of the default and change the color, but that...
Sorry, but there aren't documentation about car modding and I can't even modify the liveries for the original cars. PD. Sorry for my English.