A method for improving fuel-efficiency during a temporary stop may include dividing, by an engine control apparatus, a neutral control condition into a neutral control entry and a neutral control release during a D-stage temporary stop, determining, a neutral control entry D-stage target RPM at a time of the neutral control entry, and a neutral control release D-stage target RPM at a time of the neutral control release, and RPM shifting the neutral control entry D-stage target RPM to a speed gradient conforming to a transmission clutch release time of a transmission control apparatus at a time of a neutral control after the neutral control entry and RPM shifting the neutral control release D-stage target RPM to a speed gradient conforming to a clutch coupling time of a transmission by the transmission control apparatus at a time of a neutral control after the neutral control release.