Does cruise control save you fuel?

The price of both petrol and diesel remains at an all time high and as we head into the festive season many motorists will be looking at ways of saving fuel. 

With many South Africans getting ready to hit the road to holiday destinations around the country it is important to bear in mind that certain technologies designed to make the lives of drivers easier, could actually cause motorists to use more fuel. One such technology is cruise control.  

Most vehicles these days are fitted with cruise control, either in the conventional sense where the system merely maintains a set speed or more advanced systems that utilise radar or camera systems to maintain speed and distance within certain parameters. These systems are great for easing the driver workload and allowing drivers to maintain a constant speed over long distances while also ensuring that one doesn't inadvertently creep over the speed limit, but the way they maintain speed is not always the best for the vehicles fuel consumption. 

While maintaining a constant speed and not accelerating or decelerating unnecessarily, which cruise control does, is great for optimising fuel consumption, this is only the case when driving on a constant flat surface. However, on inclines, cruise control is slower than a driver to react and can over compensate by increasing engine speed or dropping a gear unnecessarily. For example, when a fuel-efficient driver reaches the top of a hill, they will decrease the pressure on the accelerator much faster than what cruise control can sense a change in the gradient. 

When traversing undulating terrain an experienced driver will let the car increase speed slightly on a downhill in order to carry momentum when they reach the uphill, with no change of the accelerator position. In the same situation cruise control will apply the brakes to slow the car on the downhill and will then have to accelerate to maintain that same speed on the uphill, resulting in more fuel used. 

In addition, if cruise control, and especially radar based systems are used in moderate traffic they will constantly adjust the speed, sometimes erratically, which is also not good for your overall fuel consumption figure. 

When travelling long distances and it is necessary to constantly adjust your speed due to road conditions, elevation changes or traffic, driver anticipation and the correct following distances will likely yield a bigger saving than relying on cruise control.  

On the flip side, when tackling those long flat stretches through the Karoo, cruise control will do a great job of ensuring a constant speed is maintained. Cruise control certainly has its place but before deciding to use it, assess the driving conditions carefully if fuel consumption is your number one priority.