It is pretty cloudy in the photo but I'm almost positive you have guard green. Ford has Magnetic Metallic paint code J7 which is gray and Guard Metallic paint code HN which is the same gray base just with a subtle green additive mixed in the paint. I have a guard green mustang and in overcast weather/when the car is dirty it appears gray but in direct sunlight it shines a fantastic greenish pearlescent color (not as green as the Bullitt mustang though). I bought my car thinking it was gray until I cleaned and polished it a few days later and wow what a difference it was in sunny weather. Looked up my VIN# and sure enough it was Guard Metallic. Also, Ford only had Guard on the mustang for 2015 and 2016 and then was discontinued. Probably because they were getting ready for the green Bullitt a few years later for 2019. Guard isn't a mustang specific color either, it was also found on the F150 and Fusion of the same years. Not a very popular color as sales were not high on the Guard models and the vehicle needed to be relatively clean in direct light to really see a difference. Oddly enough Guard has returned for 2021 on the new F150, makes me wonder if they will consider having it as an option on the mustang again in the future.
Thanks for the info, I didn't dig that deep into it. It was dark when I test drove it. It looked grey at first and then I parked it under better lighting and the green came out. It looks spectacular in the sun shine, imo.
I painted mine red to stand out! Looks great with the black/brushed aluminum GT/CS rims I have. Adds a decent pop of color. Might want to consider a brighter color for the brakes if you decide to paint them again, maybe red, yellow, lime green or even white.