I think the car actually decides the colour ... I would imagine a solid yellow on a Octavia RS would be more appropriate than silver.
The Superb : ONLY in Black.
The small hatches are best in peppy solids than silvers and beige.
But a Ferrari : Only RED!!
I have had 6 cars before my Post office Red Fabia, and they have been Yellow, Red and White (all Altos!!) a Blue in a Wagon R, Ochre in a Swift, and Maroon in an Innova.
I think I will lean towards Red!!