Is it true that using cruise control lowers fuel efficiency?

I've heard that it does, and I'm just curious if anyone really knows.Is it true that using cruise control lowers fuel efficiency?
If you have it, and you do not live in the mountains, use it and you may gain as much as 14%. Here is what edmunds has to say:





http://www.edmunds.com/advice/fueleconom鈥?/a>





HTH





CharlesIs it true that using cruise control lowers fuel efficiency?
Cruise control is constantly changing between acceleration and deceleration to keep the set speed. For the most part, I would believe that it wouldn't change it all that much, but the weather could make a difference, but rarely is it noticible in constant similar weather.
Yes, cruise control does lower fuel efficency, especially in areas with hills. Cruise control only reacts once you've dropped under the cruise speed, obviously, and can't slowly accelerate to go up a hill nor take advantage of gravity once you go down a hill. It causes your drivetrain to downshift quickly, raising the rpm's much higher than necessary because it anticipates the hill to never end, where as you can slowly accelerate before hills and let off at the top.
Cruise control usually increases mileage because it can keep a steadier control on the accelerator than you can.
Yes, this is well understood, and the truth is the opposite of what you have heard.





Cruise control on the whole increases fuel efficiency by making the speed of your vehicle more consistent and minimizing the need to add power on uphill slopes.
That it true. If your the type of person that accelerates a lot and brakes a lot, you can use cruise control to your advantage.





Hope this helped!
It depends on the persons manual driving style, and grade profile of the trip and to overall efficiency in and around the resultant operating point of the motor.





Could be either without knowing those three things.





Typically, for realistic scenarios it is a small disparity between the two, assuming that both trips had the same overall average speed.





For aggressive drivers, they would always benefit from the uniformity offered by the cruise controller.
That's BS (not what you've heard, but rather the above answers)! Doesn't need to add power on uphill slopes? How do you think that it maintains that constant speed? By constantly adding power, and reducing power. It just does so automatically. The constant acceleration/deceleration to maintain that constant speed just sucks up your gas. One can't possibly be that vigilant with their foot.





I suspected this once, and did a test on about a 300 mile trip. On the way over, I used cruise control the whole way on the interstate. I got 28 mpg, or something like that. On the way back I did not use cruise control at all, and I got about 33 mpg. Those numbers might not be exact, as this was almost 20 years ago, but the difference was significant. The car was a (then) late-model Honda CRX Si.
It is true that using cruise control lowers fuel efficiency. When paying close attention to your vehicle just think about it. Have you noticed the acceleration when you are going up hill and when you have to apply the brakes and then resume the cruise control? When the vehicle is being driven manually, the acceleration isn't quite as drastic unless you are a person that drives your vehicle in a harsh way. I would imagine that there is extra fuel being used for this same action in cruise control. If not, it sure feels as if it is. Ask yourself, does my vehicle work harder with or without my help? I'm thinking that if little things like bad tires can make the vehicle work harder and burn more fuel, than the vehicle working harder because of cruise control would do the same.
I haven't done research or anything on it... but i would assume yes. Reason being, when using cruise control - your car automatically maintains the same speed you set it on (in which for most cars you must be travelling at 30 + mph). Thus, upon going up hill your car would automatically accelerate until it reaches (for example) 35 mph. Once it hits that speed it lets off the acceleration - and once it drops below 35 mph, it accelerates again. Constant acceleration of the gas causes fuel to be pumped into the engine inconsistently - which in turn lowers fuel effciency - its like stop and go traffic (that's why you get better mileage on freeways/highways than you do in the city). Vise versa when going downhill. Your car switches to a lower gear to slow the car down to maintain your 35 mph speed, but when switching to lower gears - your RPMs go up and of course when RPM is high your using more fuel. Which of course isn't as effective as utilizing Neutral and coasting down the hill (of course if its not too steep).


So, overall, I'd say it does lower fuel efficiency when driving up and down hills but you probably gain fuel efficiency if driving on a flat level highway - because it maintains a consistent pump of gas contrary to your foot.





That's why I enjoy driving a manual transmission - reason being you can control the power when needed.
Cruise control actually increases fuel efficiency in most cases. This happens because while in cruise control your vehicle is at a constant speed eliminating the acceleration and deceleration that occur when slow down and speed up. It is those situations in which your vehicle uses the most gas for the least amount of movement. So don't be afraid to use cruise control on those long trips down the highway, you'll actually be saving yourself gas.
Cruise control increases fuel efficiency by 10-15%. Its the same logic as using a water sprinkler to water your lawn against using a hose.





Cruise control helps in controlling the amount the gas thats sent to the combustion chambers and no gas is wasted unlike without cruise control where you manually control the gas pedal and the control of the gas injection is erratic considering your driving style.





If you are a very good driver, who does not race or increase/decrease speed all of a sudden, there will not be much of a change in the gas efficiency compared to that of a Cruise control driver.





-Aski
I would say yes , because i just made a 150 mi trip, i have a four clinder car, every hill the overdrive would kick down and the rpm would go from 2000 to 3000. If idid not use cruse i could keep it in od with out losing to much speed