Who really needs a four-wheel-drive vehicle?

By dpa | 22 December 2017


BERLIN: Cars with four-wheel drive are becoming increasingly popular with each passing year.

The number of four-wheel-drive vehicles in a country like Germany has has increased from 2.95 million to 4.33 million in the last five years, based on data from the country's federal transportation ministry.

This increase is partly due to slick marketing from carmakers, according to the ADAC, Germany’s largest automobile club. But it's also a result of constantly improving four-wheel-drive systems. At the same time, the ever-increasing popularity of SUVs is also pushing forward four-wheel-drive development.

But who really needs four-wheel drive in everyday life? And who else can get by just fine with electronic traction assistants?

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When it comes to driving behaviour, four-wheel drive has some clear advantages over front and rear-wheel drive, namely that it generally offers better traction and safety, says Joern Getzlaff, a professor of vehicle technology at the Zwickau University of Applied Sciences.

Due to the distribution of forces over four instead of two wheels, more driving force can be transmitted by the engine. Four-wheel-drive cars handle better when turning, and offer much better acceleration, adds Getzlaff.

On the other hand, four-wheel-drive cars are more expensive than their front or rear-wheel drive counterparts. "Since they need a cardan shaft, a transfer gearbox and more differentials, they are quite mechanically complex," says Getzlaff, which also makes the cars heavier and increases their fuel consumption.

In short, a four-wheel-drive car offers advantages in handling in exchange for increased weight, greater fuel consumption and a higher up-front cost. So for whom is it worthwhile?

"All-wheel-drive has advantages in many situations," says Christian Anosowitsch from Mercedes-Benz, noting that it offers improved safety in adverse conditions, such as when driving on wet roads. Dieter Weidemann, head of all-wheel system development at Audi, agrees, noting that all-wheel drive offers added value in any day-to-day situation.

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In the ADAC’s view, however, four-wheel drive is not necessarily beneficial in just any situation; it mostly depends on where you live and what you drive. Four-wheel drive is the clear choice if living near mountains or on steep slopes, while those who regularly pull heavy loads such as horse trailers or caravans, can reap the benefits of its better traction.

But in terms of having proper traction under normal circumstances, the ADAC considers rear- or front-wheel drive to be sufficient for the usual, everyday routes that drivers will tend to cover. Getzlaff sees things similarly: in the majority of driving situations, two-wheel drive is enough.

All-wheel-drive systems aim to distribute torque to the four wheels as effectively as possible, and the majority of modern four-wheel-drive vehicles use electronically controlled multi-plate clutches for this purpose.

"They have established themselves because they work with ESP," says Getzlaff. Opel, for example, has installed two multi-disc clutches in the four-wheel variant of the Insignia, which precisely direct the required force to each wheel.

Multi-plate clutch systems are primarily intended for occasional off-road operation, says Getzlaff. For longer off-road trips, however, classic all-terrain vehicles may make a better choice, featuring "traditional systems," as Getzlaff notes. These systems have individually controllable limited slip differentials.

And what about electronic aids? Since late 2014, says Getzlaff, Electronic Stability Programs (ESP) have been mandatory for every newly registered car in Europe. While electronic aids can indeed improve traction, they cannot replace four-wheel-drive systems, explains the ADAC. According to Getzlaff, they can help a car perform better as it approaches its limits – but cannot push these limits further.

All-wheel drive is vital in offroad conditions like such as this.
All-wheel drive is vital in offroad conditions such as this.

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