ΔE 11.4, fair: the same colour family, but not a straight swap. Medium Gray is a little darker, more saturated than Iron Man.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Medium Gray is a little darker, more saturated than Iron Man.
The same difference applies the other way round: Iron Man is a little lighter, more muted.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Iron Man on the colour wheel See Medium Gray on the colour wheel
All matches: Iron Man equivalents · Medium Gray equivalents