Aluminium

Thanks!

I also found press release about Nocturne:

The Veyron “Nocturne” strikes with an extraordinary partition of surfaces never used so far, giving the car a new dimension of lateral length. Bugatti is experimenting with galvanized side windows continuing the line of the polished aluminium upper body parts to the rear of the car and contrast vividly with the uni black of the side- and door-panels and the roof. Added to that is the hood, also covered in polished aluminium which emphasizes this impression of elegant length. Special polished custom rims at the exterior and a futuristic interior dominated by a black nanocoated magnesium dashboard and a centre console in galvanized Platinum complete this unique combination of individualized modern design.

So it could be a magnesium cause it's colour is similar to the colour of aluminum.

This are the nocturne interiors, not polished aluminum than the normal and standard center console.
as you read on the press release the nocturne has "black monocoated magnesium" (this is the exteriors ring of the dashboard). the center console is in galvanized Platinum..