Can anyone help me identify what set this bag with grey and dark red pieces belongs to? Can anyone help me identify which Lego set this bag belongs to (it has two smaller bags inside)?
As the comments said: it's hard to tell. 

But based on

Plate 2x14 in light buish gray, 

Slope, Curved 10x1 in light buish gray and 

Slope, Curved 3x1 No Studs in  Dark Red 

i believe it is bag 2 from 

75012 BARC Speeder with Sidecar