Blue is my favorite. Sporty, but not blatantly so. the definition of "cool".
Red is a close second. VERY close. Sometimes blatantly sporty can be good.
Black is always classic, and makes pretty much any design look good, but it hides details, and requires endless care.
Claret maroon red is nice, too. Kind of a "rich" color.
White is nice. Normally I don't like white cars at all, but a white/black SVX is natural for the design of the car, with the pearl. If it were a plain white, it would look like a refrigerator.
Silver looks similar to white. I used to like silver, but I think it is too over-used. It is the new beige for cars.
Yellow is difficult. The right car in the just-right shade of yellow can be very cool, but too banana-colored is odd, and too orange-tinted makes it look like a highway-services utility vehicle, and not every car design suits yellow.