I have 2 like this in a litter. Grey and fawn hairs. What is this color called?
That looks like a cream (which is dilute blue non-extension aguoti). But it could also possibly be a lynx (which is dilute chocolate agouti). They can look very similar, but lynx has a more pinkish-gray cast and "rings" in its fur, while cream does not.
I don't have an image of a cream, but here is an orange/red. A cream would be much paler than this, but would only have the surface color and the lighter undercolor, without any rings:
Ring color in lynx is subtle because the tipping is lilac (pale, dilute chocolate), the middle ring is pale, dilute fawn, and it doesn't usually show up very well in young bunnies. Try blowing into the fur along the flanks, toward the rear end of the bunny. Here is an image of a very young lynx Satin whose ring color is just starting to show up:
Here is the same image with the "rings" marked:
This rabbit is not a great example of lynx because its surface color is unusually dark, and in these photos has more of a blue cast (in life it's a pinkish dove-gray), but it'll give you the idea of subtle ring color.
Here is what the lynx color looks like in a mini rex: