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.
I’m not talking of hills. It’s constantly doing this resistance feeling flat up or down. No other car Ive been in does this. It just stays at the set speed. I actually hate this about my car it drives me nuts.
It must be the right amount of resistance, else the speed wouldn't be holding steady. Are you saying it "stays at the set speed" like the way a high school classmate of mine used to drive, by alternately pressing and backing off the go pedal? She'd never notice she was doing it, and the car'd be doing the right speed on average, and if you were her passenger your head would be continually jerked back to the headrest and forward again for the whole trip. If your cruise control is having that effect, clearly something isn't working as designed. Do you have some engine issue where it isn't responsive right away, and then more power comes after some delay? I could see that interacting with the cruise control in a way that might result in a hunting effect.
Cruise control won't use the friction brakes to slow down, though. Regen, yes; engine braking, yes; but it won't apply the friction brakes to hold your cruise speed. The ordinary cruise control, I mean. If you've got the adaptive-cruise-right-down-to-full-stop feature, then it has to actually brake sometimes. Didn't sound like the OP meant that feature though.
Is it possible that the Dynamic Cruise Control is what you are experiencing? The sensitivity of that can be adjusted and depending on the setting, it would respond the way you described as it responds to traffic and even vehicles parked on the side of the road. I have experienced it doing this occasionally especially when driving down a curving road, and when cars merge in front of me on expressways and are accelerating quick enough to cause the car to start to slow down and then resume before it actually decreases speed to any significant amount. I hope that makes sense.
