Dark Concrete vs Engine Gray

How close are they?

ΔE 7.3, close: similar, with a visible difference side by side. Engine Gray is a little darker, more saturated than Dark Concrete.

Can I use Engine Gray instead of Dark Concrete?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Engine Gray is a little darker, more saturated than Dark Concrete.

Can I use Dark Concrete instead of Engine Gray?

The same difference applies the other way round: Dark Concrete 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.