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Does cruise control save fuel?

The technology is common, but its correct usage is not, writes EUGENE HERBERT, MD of MasterDrive.

South African motorists find themselves paying more for both petrol and diesel again. 

Internationally, many countries face their own steep increases in fuel prices, although not as extreme as in South Africa.

Consequently, motorists in the UK are being warned that technology in vehicles that can save fuel needs to be used correctly for this to be a reality. Incorrect use could actually cause motorists to use more fuel.

The technology being referred to is cruise control. While it can boost fuel economy considerably, this is only when driving on a constant, flat surface. On inclines, cruise control is slower than a driver to react to gradient changes. When a driver reaches the top of a hill, they decrease their pressure on the accelerator much faster than what cruise control can sense a change in the gradient.

The same applies in driving with traffic. 

Firstly, cruise control is never recommended in heavy traffic because of the potential for something to go wrong. If, however, a driver uses cruise control in moderate traffic and is consequently adjusting or stopping and restarting regularly, they will not get the most fuel saving benefits from cruise control, safety concerns aside.

A Natural Resources Canada Study found cruise control could potentially reduce fuel consumption by 20% – if used correctly. If you are consistently adapting your cruise control between 110km/h and 120km/h, for example, as opposed to keeping it at a consistent 120km/h, you are unlikely to see this saving. If you find you regularly need to adjust your speed, driver anticipation and correct following distances are more likely to get a bigger saving than using your cruise control.

Yet, if adaptive cruise control (ACC) manages following distances for you, can the same be said for ACC? 

According to a study conducted across Europe in 2012, it found the sensors that adapt the speed according to traffic, result in fuel savings. Yet, most of these studies are conducted in open highway settings where there are minimal adaptions. Additionally, the savings are around 2.8%, thus negligible at best. More research needs to be conducted in real-driving settings.

Thus, there is a place for cruise control in saving fuel and also for consuming more. 

Before deciding to use cruise control look at the driving conditions and decide whether they allow for it. Also do not sacrifice safety for reducing fuel consumption, for example, using cruise control in wet weather. There is a place for all car technology that requires correct use to get the most benefit from it.

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