Indeed; he is nuts. He's probably the same nut that predicted the final days of white cars.
Cheaper manufacturers cut costs by offering dark grey polyester or very cheap black leather without choice because that way they make a greater profit per unit. Witness the witless surcharge for metallic paint.
Most dealers order silver with black interior because they think it will offend the least number of people. Such a combination rather offends me. I loathe and detest grey polyester interiors and black makes it hard to find items.
Maserati offers a very nice Zegna silk upholstery in the Ghibli; Rolls-Royce and Bentley offer any colour you like and M-B Designo will create your interior in a very wide range of materials and colours.
Even Mazda offers a rather smart white upholstery.
Clearly only grey people buy grey interiors.
Regards,
Brian