Antonyms for the phrase "stepped on the gas" include "slowed down," "braked," "eased off," and "coasted." These opposing actions involve reducing speed, decreasing acceleration, or even stopping entirely. While "stepping on the gas" may connote a sense of urgency or a need for speed, these antonyms suggest a more measured or cautious approach. They may be appropriate in situations such as approaching a red light, encountering heavy traffic, or navigating a treacherous road. Choosing the appropriate antonym depends on the context and the driver's goals, whether it be arriving at a destination quickly or safely.