Inform them right away, before they start making excuses or might start making.
Blue looks nice, not the wine red.
IMO: as for the people buying - there are very less who buy it as 3rd or 4th car, these colours look better where ppl have more than 2cars/rides.
For the heads with no or 1 - like to gets settles on White/Black or Silver, having better resale compared to others.