Honestly I have always gone to a good auto upholstery supplier (often time upholstery shops carry auto and home products). Some place like Keystone brothers or similar. I show it to them and they will cut a few small samples of what they have for me to take out and match in the sunlight, inside in their lighting, etc. They almost always have some close enough that it looks identical. I have seen OEM carpets vary in color more just from aging.