Step on it and Step on the gas

Step on it verb - Move fast.

Step on the gas and step on it are semantically related in moving topic. In some cases you can use "Step on the gas" instead a verb "Step on it", when it comes to topics like get cracking, drive at full speed, run away to escape.

Step on it and step on the gas are semantically related in moving topic. You can use "Step on it" instead a verb phrase "Step on the gas", if it concerns topics such as drive at full speed, run away to escape.