I don’t know the right words. Sorry. But when using cc the car jerks all the time. Not jerk but as I said I don’t know what to call this. You feel it have resistance a lot. The speed stays the same. But you can feel it have resistance. Like I’ll be going. Set 45 mph. It feels like the break comes on for a split second. Then goes away. Does this all the time. every other car I ever been in don’t do this ever. Cruise just works. Just goes. So I have no idea what’s going on.
If the speed stays the same, the cruise control is doing its job. Cruise control in many older cars acted only on the go pedal. It would make sure the car didn't fall below your set speed, but the car could still end up going faster if, say, the road turned downhill. The older cruise control did not have a way to hold your speed back to the set speed. (Gen 1 Prius was like that, too.) In gen 2 and later Prius, the cruise control also knows how to actively hold the car back from exceeding your set speed. Normally it will do that by capturing energy into the battery, so it can be used again when power is needed. If the battery fills and can't be used to capture more energy, the cruise will transition to using engine braking for the same purpose. The amount of resistance it will apply this way is limited; depending on your set speed and the steepness of grade, you can always find a downhill where your speed will pick up even with cruise set. You can apply more resistance by using the brake pedal. Even when there's plenty of battery capacity to accept regen, you can get a lot more regen via the brake pedal than cruise will ever apply on its own. The most regen that cruise will apply—at least in the Prius generations I'm most familiar with—seems to be right around 13 kW or so, similar to the maximum power the engine is able to dissipate when spun as a vacuum pump. That way, if you are on a downhill and the battery runs out of capacity to accept more regen, you don't notice much change in the car's slowing rate as it shifts to engine braking (though you do hear the engine spool up, which freaks some people out). Even though the speed is held constant: holding speed constant on a downhill feels to the seat of your pants just like slowing; holding speed constant on an uphill feels like accelerating. That's just the equivalence principle in physics.
