I recall that there was some discussion about the red colours on Deanīs red cars, after he got the S8. At that time I couldn't spot any difference, and kept my mouth shut. As some could clearly see the shade difference.
Well, now I also see the difference. But only on my iMac 27" 5k (late 2015) display. Likely because of it's
wider colour gamut 
Best display I have ever owned. Bought it used, just before Christmas
Did I mention that looking at photos of the cars on this forum is an even greater joy? !
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Johannes
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Audi S8 -99, Pearlescent, Alcantara/silk napa leather, Burr walnut insert, Alcantara roof lining upper pack
A8 32V engine
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Jeep Grand Cherokee -98