To increase in speed or to cause to increase in speed.

गति बढ़ाना

English Usage: The car began to accelerate as it approached the highway.

Hindi Usage: गाड़ी हाईवे के पास आते ही गति बढ़ाने लगी।

The act of accelerating; the increase in speed.

गति वृद्धि

English Usage: The sudden accelerate in the vehicle surprised the driver.

Hindi Usage: वाहन में अचानक गति वृद्धि ने चालक को चौंका दिया।