Are you selling a color or a car? Forcing the sentence until the impossible, you will be able to say
Voy a vender mi rojo coche (never "de coche")
But this is absolutely odd. As a rule you place the color after the noun and we would never be wrong. It's true that in a literary way some times it's possible to find some example reversed, as for example "mi blanca paloma" but this does not happen often. It's a like-poetic way. But at this point you should not be concerned by this way.
You would not use the reflexive pronoun for vender - to sell, but there is a closely related verb that you can use reflexively - comprar - to buy.
Me voy a comprar un coche rojo.
I'm going to buy myself a red car.
Le voy a comprar un coche rojo.
I'm going to buy him a red car.
Te voy a comprar un coche rojo.
I'm going to buy you a red car.