I have a question about cruise control. I currently drive a 2014 Jeep Patriot but have had this same issue on previous cars I have driven, both newer and older. After temporarily disengaging the cruise and then hitting resume, the transmission will downshift to speed up to the pre-set speed. It does this with even less than a 5 mph decrease in speed. Is this really a gas saving feature or would it be best to bring the car back up to speed gradually prior to hitting resume? It can really be annoying sometimes.
It is not a gas usage feature. That is just how some work. If it really annoys you then just bring the vehicle back to the speed you want and reset cruise . I doubt if the amount of fuel used or not used by the downshift is enough to worry about.
The cruise control wants to get the car back to the set speed quickly so it can shift back to the highest gear to conserve fuel. I usually accelerate gently back to regular speed before resetting it myself so it doesn’t drop 2 gears for a few mph, but I’m not honestly sure how much fuel I save doing that. Overall, though, I would say yes, cruise control definitely does save fuel, especially driving long distances on the highway (like driving to vacation)