The black-only paintjob is what makes the GN stand out... and is also why they are so quickly recognized on the street.
A GN that isn't black... is... well... just another T-type.
My first Turbo Buick was an 86 T-type in gray... I sold it because I got tired of the grampa-car comments... and questions like... "Is that a Monte Carlo ?" or "Is that as fast as a Grand National ?"
I NEVER get questions like that when I'm actually DRIVING a Grand National.