I get better gas mileage without cruise control. Cruise control is dumb for all intents and purposes, if you're on an uphill section of highway it sees speed decreasing and accelerates without consideration for engaging the turbo or not. Not using cruise I can feather the throttle and keep the engine out of boost whereas cc just accelerates to get back to the speed setting as soon as possible. In theory your statement would be correct in a completely flat landscape but for me I can beat cruise control any day where I live.It does. It keeps your acceleration constant on fairly straight roads for long stretches. If you are driving for like an hour or more usually your speed fluctuates as your foot tires and you put less pressure on the pedal then you correct it.