Kylo Ren's shuttle is black:
I don't remember seeing any white shuttles in the film, yet we have these:
Do we ever see any white shuttles in TFA and if so, when?
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Pablo Hidalgo recently confirmed on Twitter that, because of the different production schedules of toys versus films, the shuttle toy could not be fixed in time:
@stolpskott: What about the Lego Hovertank?
@pablohidalgo: Toys/products have a much longer lead time than books. They couldn't fix it in time. Same story behind the white Kylo shuttle.
Presumably one of the zillions of departments working on the film changed Kylo's shuttle colour, but they were unable to correct the toys in time. Such is life.
As you can see from this LucasFilm-created TV advert, Ren's shuttle is actually a slate-grey in colour, rather than black. It's not impossible to imagine that the person making the poster (which is a low quality artwork that was "leaked" prior to the film's release) mistook grey for white. In another poster by the same artist, you can see that the colour balance is slightly darker and leaning much more toward a light grey.
As to the model in your picture, that's a Titanium "Black Series" diecast model. They're notorious for colouring the Empire's grey ships in white.
In your movie grab, Kylo Ren's shuttle isn't even as black as these birds from a free stock image page
They are gulls, which are about the same colour grey as the front-lit model of the shuttle is.
I don't remember seeing the shuttle in the movie in as good lighting as the toy, only either at night or dramatically coming out of the light.
I suspect that both are supposed to be a battleship grey, and the toy is perhap a shade too light. Neither is black nor white.
Having watched it again, I did find one scene where the shuttle is shown in decent light, and it is around 35% of the way from white objects to black objects in the scene, whereas the toy is around 95% of the way from black to white (assuming the box is black and the background white). So the toy, which claims to be the same shuttle, appears to be much too white.