I've had such good luck with my XK8 interior and using the duplicolor vinyl and fabric paint that I'm thinking about trying it on my XF door cards and part of my lower dash.
I have the dove grey and black interior but I've never been totally happy with all the light grey. The panels between the front and rear doors are black but the doors are all grey. I want to paint the lower portions of the dash beside the center console black and continue it all the way to the back doors. Leaving the handles in grey and the small piece beside the stainless panels grey also.
My friend has an E class Mercedes and its also grey and black interior but its more black.

 

SEM products seem to adhere and feel better than Duplicolor - proper prep is key