As a fan of Subarus, I'm a big fan of WRC Rally Blue, the official color of Subaru's World Rally Championship effort.
A Mazda 3 is hardly a WRX (MS3 perhaps)... so it's perhaps overkill but I do like certain cars to have some pop - I'm OK with it on a Mazda 3.
I'd have to see the blue in the steel to get a better idea but I voted for Celestial Blue, Gunmetal reminds me of something I've seen of Chrysler Sebrings circa 2000 which may be the ultimate offence.