My preference would be for the colour to match the tag, but hey its a real world. It wouldn't stop me buying the car but I would use the incorrect colour as a barganing point to TRY and get the price down.
At the end of the day if you intend to keep the car does it matter? Do what you want, it is your's after all, therfore it is only you it needs to please.
Just my two bits.
nassi