We experimentally study the group time delay for a light pulse propagating through hot {sup 87}Rb vapor in the presence of a strong coupling field in a {lambda} configuration. We demonstrate that the ultraslow pulse propagation is transformed into superluminal propagation as the one-photon detuning of the light increases due to the change in the transmission resonance line shape. Negative group velocity as low as -c/10{sup 6}=-80 m/s is recorded. We also find that the advance time in the regime of the superluminal propagation grows linearly with increasing laser field power.