Cruise control. Does driving with cruise control on reduce fuel consumption?

Every driver wants his car to consume as little fuel as possible. Its consumption is influenced not only by driving style, but also by the use of many accessories that increase travel comfort. It is not always enough to take your foot off the gas to reduce fuel consumption. How does using cruise control affect fuel consumption? As it turns out, there is no clear answer.

Eco-driving - grandmother said for two

On the one hand, economical driving is not that difficult, and with a few habits, you can achieve excellent results - low fuel consumption and increased range on a single gas station. On the other hand, you can easily jump and fight for survival in normal driving.

For example, air conditioning can increase fuel consumption by one, two or even three liters of fuel per 100 km. Of course, it is worth using it wisely to minimize consumption, but giving up pleasant coolness on a hot day in exchange for saving 5-10 zlotys per 100 km is a big exaggeration, because we not only reduce our own comfort and passengers, but also risk our safety – heat affects the driver's reaction, well-being, in extreme cases it can lead to fainting, etc. Other equipment, such as radio, sound system, lighting, etc., also affects fuel consumption. does that mean you have to give it up?

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It's much better to keep your car in good condition, use its features and systems wisely, and follow a few obvious rules. Dynamic driving increases fuel consumption, but this does not mean that you need to stretch and drive in 50th or 60th gear at a speed of 5-6 km / h - it does not make sense. Relatively quickly reaching the set speed will allow you to drive for a long time at a constant speed in the optimally selected gear, and this significantly reduces consumption. In addition, it is worth closing all windows (open windows increase air resistance), empty the trunk of excess ballast, use the air conditioner wisely (avoid maximum power and lowest temperature), maintain adequate tire pressure and, if possible, brake the engine, for example, when entrance to the traffic light. On the other hand, cruise control can be useful on the road. But is it always?

Does cruise control save fuel? Yes and no

In a nutshell. The use of cruise control, of course, increases the comfort of the trip, gives rest to the legs even during short trips out of town. In the city, the use of this add-on is rather unnecessary, and in some cases even dangerous. In any case, for people who travel a lot, cruise control is undoubtedly a great and very useful accessory. But can it reduce fuel consumption?

It all depends on the type of cruise control and the route, or rather, on the terrain in which we travel. Having a car with the simplest cruise control without any additional "amplifiers", driving on flat terrain without slopes and with moderate traffic, fuel consumption may decrease somewhat. Why? The cruise control will maintain a constant speed without unnecessary acceleration, braking, etc. It recognizes even the slightest speed fluctuations and can react immediately, minimizing acceleration to a greater extent. In normal driving, the driver cannot maintain a constant speed without constantly looking at the speedometer.

Cruise control will provide speed stabilization and engine operation without variable loads, which will result in a certain difference in fuel consumption over a distance of several hundred kilometers.

In addition, the psychological aspect will also work. With cruise control, you won't want to overtake too often, pressing the gas to the floor, we will treat the trip as relaxing, even if the speed is a little below the limit. Sounds weird, but it works in practice. Instead of controlling your speed all the time, overtaking, although the other driver is driving for example 110 instead of 120 km / h, it is better to set the speed on the cruise control lower, relax and enjoy the ride.

At least in theory

It will be completely different when we use traditional cruise control on slightly more varied terrain with a lot of descents, climbs, etc. They do not have to be very steep, but a dozen kilometers of driving is enough to significantly increase fuel consumption. Cruise control will try by all means to maintain the set speed when climbing, even at the expense of maximum throttle, which, of course, will be associated with increased fuel consumption. However, on a descent, it may start to brake to reduce acceleration. A solo driver will know how to behave in various conditions, such as accelerating before a hill, slowing down on a hill, braking with the engine when going down a hill, etc.

Another difference will appear in the case of a car with active cruise control, additionally supported, for example, by satellite navigation readings. In this case, the computer is able to anticipate changes on the road and respond in advance to the inevitable change in traffic parameters. For example, upon “seeing” a car ahead, Active Cruise Control will slow down slightly and then accelerate to the set speed. In addition, when reading altitude navigation data, it will downshift earlier and cover the distance without unnecessary forcing of the drive. Some models also have a "sail" option, which can be useful when descending a hill with speed control via the brake system, etc. The operation of such solutions in rough terrain allows you to achieve better results than with traditional cruise control, but the driver's anticipation , his feelings and experience are still the guarantee of the best results.

Theory Theory…

How does it work in practice? On the occasion of another trip from Radom to Warsaw (about 112 km including a short distance around the city) I decided to check it out. Both trips took place at night, at the same temperature, for the same distance. I drove a 9 Saab 3-2005 SS with a 1.9hp 150 TiD engine. and a 6-speed manual transmission.

During the first trip to and from Warsaw I didn't use cruise control at all, I was driving at a speed of 110-120 km/h, the traffic was very moderate both on the highway and on short distances in the city - no traffic jams. During this trip, the computer reported an average fuel consumption of 5,2 l/100 km after covering a distance of 224 km. On my second trip under the same conditions (also at night, with the same temperature and weather), while driving on the freeway, I used the cruise control set to about 115 km/h. After driving the same distance, the on-board computer showed an average fuel consumption of 4,7 l / 100 km. The difference of 0,5 l/100 km is insignificant and only shows that in optimal road conditions (both in terms of traffic and terrain), cruise control can help reduce fuel consumption, but to a rather small extent.

Cruise control. Use or not?

Of course you use it, but be smart! When driving on a flat road with little traffic, cruise control becomes almost a salvation, and even a short trip will be much more comfortable than in the case of "manual" driving. However, if we are driving in a mountainous area, where even an expressway or a motorway becomes winding and undulating, or if the traffic is heavy enough and requires the driver to be constantly vigilant, slow down, overtake, accelerate, etc., it is better to decide to drive without this assistance, even if it is active cruise control. We will not only save fuel, but also increase the level of safety.

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