If its leaking while pumping gas I would follow the filler neck hose to the tank and see if the clamp has come lose or the hose isn't sitting flush.
Its a 2012 so what about bringing it to the dealer to check out? Leaking fuel is kind of a serious matter.
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Zetec Crew #175
REP WHEN REP IS DUE
Mazda Employee and general car enthusiast.