Song Sparrow is pretty common in the area around Toluca. Sierra Madre Sparrow is not reported from that area to the immediate north of Toluca, at least in eBird. Of course that doesn't mean that Sierra Madre Sparrow could not be there.
I am no expert on these birds, but going off memory, field guides, and photos of SM Sparrow vs mexicanus Song Sparrow, I would think your bird is a Song Sparrow as well. When I was birding in that area I made certain to hear my lifer Sierra Madre Sparrows as well as just see them to remove doubt, as ID is definitely not trivial.