The new Touareg¹: the advantages of all-wheel steering, roll stabilisation, and air suspension
He has turned his passion for cars into his profession. Dr Friedbert Weizenecker, freelance car journalist and editor of “Der-Autotester.de”, has been testing the new Touareg for us. Check his report, focussing on the technical innovations of the new Volkswagen flagship:
“For engineers, technology has sometimes been an end in itself. Whenever somebody asks them how something worked, they’d talk at great length. But whether or not you’d be able to understand it is another thing. Many engineers become much quieter when asked about the specific use of an invention. They don’t seem to be quite so interested with the advantages for the customer. They get excited about elegant function. Marketing experts, on the other hand, look at technology from a user's perspective. What is the customer able to do with it? What do they gain? Only once there is a clear response to this question, does it make sense to integrate technical innovations into products. This is also the case with cars. And the wonderful wisdom applies to the following innovations, which have been developed by Volkswagen engineers for the new Touareg.
The suspension was redeveloped in many areas in order to perfect both comfort and dynamic characteristics. At additional cost, Volkswagen again offers four-corner air suspension with electronic damping control. This suspension has had a major overhaul using the latest technology. The active roll compensation with electromechanically adjustable anti-roll bars is also included in the complete redevelopment. Volkswagen has also redeveloped the all-wheel steering which allows large SUVs to feature similar agility and manoeuvrability as a compact SUV. I will explain as clearly as possible how these wonders of technology work and what advantages they have to offer users.
Aluminium is known as a particularly light metal. When it is used in vehicle construction, it reduces the overall weight.
A lighter vehicle with the same performance moves much more dynamically. The lower weight also has a positive impact on the fuel consumption as the vehicle only has to move less weight. This applies not least for the design of the suspension. Five-link axles of lightweight aluminium-steel construction are used in the new Touareg.
The active roll compensation (almost) transforms the SUV into a sports car
As already mentioned, one complete redevelopment is the adaptive roll compensation.
Volkswagen has called this system the electro-mechanical active roll compensation (eAWS). The two most important components of eAWS are the anti-roll bars on the front and rear axles. Conventional suspensions are fitted with steel anti-roll bars at the front and at the back which reach from one end of the axle to the other. When cornering or when only one side of the vehicle is driving over very uneven road surfaces, two ends of the anti-roll bar twist relative to one another. The kinetics ensure that the vehicle’s tendency to roll in bends is reduced.
Thanks to the eAWS active roll compensation in the new Touareg, this works even better. During my first test drives on paved roads, the Touareg, in spite of its height, provided me with the driving feel and body roll you would expected from a sporty saloon. You couldn't give an SUV on the road a better compliment. There is the feeling in the Touareg that the centre of gravity is much lower than it actually is. This makes it really fun to zoom along the winding Tyrolese roads with this huge SUV. Of course, this fun is also helped by the powerful 6-cylinder diesel engine which puts up to 600 Newtonmeters on the road.
You sit there in a spacious vehicle, accommodating bag and baggage, but you (almost) feel like you're sitting in a sports car. It's really impressive what the new suspension technology makes possible in combination with a modern diesel engine (which fulfils the current strictest emission standard: 6d temp). The limits of physics appear to have been stretched for the Touareg.
Electromechanical anti-roll bars provide for quiet running
In order to stretch the limits of driving physics, the Touareg, fitted with eAWS, features electromechanical anti-roll bars at the front and rear axle. A central control unit coordinates their use. The two ends of each anti-roll bar are connected to one another by a step motor. Depending on the driving situation, the step motor twists the two ends of the anti-roll bar relative to each other, to stiffen or even be decoupled. The 48 V supply needed to activate the powerful step motors is built up temporarily using capacitors. This is how the roll in the Touareg is significantly reduced by the anti-roll bars. In addition, the directional stability is improved on roads which are uneven on one side. The articulation of the axles and the traction can be improved by electromechanical decoupling of the anti-roll bars when driving off-road.
All-wheel steering alone doesn't reduce the size of the turning circle
Another innovation on board the Volkswagen is the optional all-wheel steering.
Depending on the driving scenario, all four wheels are steered at the same time. The all-wheel steering contributes to making the Touareg one of the most agile large SUVs. Mostly it influences two driving situations: speeds under 37 km/h and speeds above this figure. This seems to contradict itself, but it doesn't. This is because the system works thus: up until 37 km/h, the rear wheels automatically turn in the opposite direction at the front wheels. This improves agility and manoeuvrability. Thanks to the all-wheel steering, the turning circle is reduced by a metre from 12.19 to 11.19 metres. This is a very small turning circle for a vehicle of these dimensions – the circle is even thirty centimetres narrower than that of the Tiguan. If the speed is increased to more than 37 km/h, the rear wheels turn automatically when the vehicle is steered and are in the same direction to the front wheels. This makes vehicle handling much smoother. When changing lanes, the Touareg sits better on the road. This also applies to fast overtaking and when making sudden manoeuvers to get out of the way. Isn't fantastic that you can combine the fundamental advantages of large and small cars in a single vehicle class?
Air suspension brings the Touareg to the right height
The new generation of four-corner air suspension doesn't just significantly increase comfort. It also improves aerodynamics. And driving on rough terrain can be better mastered. I think it really is worth investing in a more expensive vehicle. But how does this work?
The new, open air suspension system works quickly and silently. It is unperturbed by changes in temperature and fluctuations in pressure (e.g. in mountainous areas). Normal or comfort height should be the standard setting. For journeys with more rough terrain, the off-road height increases the height by 25 mm, while the special off-road height increases the height to 70 mm. With speeds from 120 km/h, the suspension automatically lowers by 25 to 35 mm (low height). This lowers the aerodynamic drag and adapts the vehicle handling. The loading height (minus 40 mm) can be used for better ergonomics when loading and unloading the luggage compartment. Which makes strained backs very happy!
Air suspension – perfect for off-road
Why is it perfect? Because it optimises the off-road parameters. What does that mean? The front and rear ramp angles increase with the air suspension from 25 to up to 31 degrees. The breakover angle also increases from 18.5 to up to 25 degrees. Because the ground clearance can be increased by air suspension, the maximum fording depth, for driving through rivers, can also be increased from 500 mm to up to 580 mm. The level of air suspension described here is activated with a turning pressure switch in the Touareg's centre console. This is child’s play and works just fine after only a short amount of practice.
And it is at this point that I would like to draw everything to a close: the purpose of the all-wheel steering, roll compensation and air suspension in the everyday driving of the new Touareg should now be clear. At least, that’s what I hope! Not everyone is an engineer.”
Dr. Friedbert Weizenecker
¹Touareg V6 TDI 4MOTION, 210 kW / Fuel consumption in l/100 km: urban 8.1 / highway 6.2 / combined 6.9, combined CO2 emissions in g/km: 182; efficiency class: C.