The first F90 without a standard option interior colour was built last week in British Racing Green with a full Fiona Red interior, VIN BS92584, so it looks like it is possible.
I was going to post earlier in the week, but this wasn't on any "public" sites at the time. You can now see the decode on
http://bimmer.work/
0490 Special painting Paintwork "british racing green", as code 312.
Z1XX Special upholstery
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Full leather Merino fiona red (nb. 7 988 501 / Sun Reflective Technology). Sewing thread fiona red (nb. 7 990 882), code 1622 D. Quilting yarn fiona red (nb. 7 990 881), code 1622 D. --------------------------------------------------------------------
In combination with option 453: Front an rear seat seat covers partially in climate leather Merino fiona red perforated (nb. 7 988 926 / Sun Reflective Technology). Sewing thread fiona red (nb. 7 990 882), code 1622 D. Quilting yarn fiona red (nb. 7 990 881), code 1622 D.
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Contrast stitching on full leather: Sewing thread black (nb. 1 905 499), code 0020. Quilting yarn black (nb. 1 963 800), code 0020.
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Upper dash board and capping of door trim leather Walknappa black (nb. 7 963 181 / Sun Reflective Technology). Sewing thread black (nb. 1 905 499), code 0020. Quilting yarn black (nb. 1 963 800), code 0020. (Without contrast stitching).
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Seam of seats according to X3.
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Remainder of spec. as full leather Merino black (code X3SW).