ΔE 37.0, loose: different enough that you should pick on purpose. Beetle Green is noticeably darker, much more saturated than Flat Aluminum.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 37). Beetle Green is noticeably darker, much more saturated than Flat Aluminum.
The same difference applies the other way round: Flat Aluminum is noticeably lighter, much 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 Flat Aluminum on the colour wheel See Beetle Green on the colour wheel
All matches: Flat Aluminum equivalents · Beetle Green equivalents