Thread resurrection based on my current experiments. I've been working on ZG flares and the rear panel trims, having epoxy primed them all a while ago. I test sprayed a rear light trim and one arch with the BMW 397 Anthracite I mentioned above. While the right sort of depth/darkness of colour and a fine metallic, IMO, it has a strong blue tint to it that makes it unsuitable. It may be that earlier versions of that BMW Anthracite (some shades date to the 70s) were a bit different, but the more recent shade I used is not right.
I then returned to various forum discussions in the US about the colour, and one that had undergone side-by-side comparisons with NOS parts in original paint and come out well was Ford Dark Shadow Gray, code CX-7039. So I ordered a can of the Ford (USA) colour (there is a Ford Europe version too but this may be different) in a custom mix aerosol from Paints4U and have given it a spin. MUCH better. Similar colour, but without the obvious blue tint. I will be using this for the ZG flares, rear panels and rear spoiler on the project Z. From the can, it has a near perfect flat/matt finish, although it may still make sense to lacquer it with a 2K satin or matt clear.