New, more efficient version of Audi's quattro four-wheel drive system will be seen first on the upcoming A4 Allroad estate
16 February 2016

Audi has unveiled a new version of its quattro four-wheel drive system that it claims provides a critical improvement in efficiency.

The new quattro system uses an electro-mechanically operated multi-plate clutch and rear gear set that combine to eliminate mechanical drag by completely cutting drive to the rear differential, and with it the rear wheels, when the driver only requires front-wheel drive.

To be marketed under the name quattro ultra, the new system abandons the widely used Torsen torque sensing system, as well as the central differential and rear differential hardware used by Audi in one form or the other since the inception of its original quattro four-wheel drive system back in 1980.

In its place is a fully networked set-up capable of analysing the driving conditions every 100 milliseconds and automatically providing either front- or four-wheel drive depending on factors such as longitudinal acceleration, engine torque, steering angle, yaw rate, prevailing traction and driving style.

Set to make its debut on the upcoming A4 Allroad prior to being fitted to the new A5 coupé and second-generation Q5, the contemporary new quattro ultra system will initially be offered on models based around Audi’s MLB (modularen langsbau – modular longitudinal architecture) platform in combination with its new high compression turbocharged 2.0-litre four-cylinder petrol engine and seven-speed S-tronic dual clutch gearbox.

Unlike the old mechanical Torsen-based quattro system, which based its operation principally around existing traction levels, the new electro-mechanical system is influenced by a much wider range of information obtained by various sensors, as well as data relating to the road provided by the navigation system.

By combining this information, Audi says its new quattro ultra system can provide predictive operation by constantly sensing whether the driver requires front- or four-wheel drive and adapting the apportioning of drive to suit. In doing so, the new system is able to run in a more efficient state than the Torsen arrangement, which will continue to be used on more powerful Audi models, including upcoming RS models from the German car maker’s Quattro division.

Mechanical developments brought to the latest incarnation of the quattro four-wheel drive system are similar those used on the four-wheel drive versions of Audi’s transverse engine models, including the A1, A3, Q3 and TT.   

They include a new electro-mechanically operated multi-plate clutch mounted on the end of Audi’s seven-speed S-Tronic dual clutch gearbox. Depending on the model, it consists of between five and seven pairs of clutch plates that rotate in an oil bath. When the plates are pressed together, four-wheel drive is activated. The contact pressure between each plate is used to distribute drive between the front and rear axles.

The front multi plate clutch works in combination with a newly developed dog gear style rear differential featuring a decoupler operated via a so-called claw clutch. When the decoupler is closed, the propshaft and differential are operated to provide drive to the rear wheels and thus provide four-wheel drive.  

When running in front-wheel drive, the front multi-plate clutch disconnects the propshaft. At the same time, a decoupling device within the rear differential opens to reduce friction and associated drag losses.

Unlike the process used by the existing Torsen torque sensing quattro system, the only rear-wheel drive components engaged when running in front wheel drive are the bevel gears within the axle and gears within the differential – the latter of which compensate for differences in the speed of rotation of the wheels during cornering.

A passive torque vectoring effect is provided to the rear wheels via selective braking activated by sensors in the ABS anti-lock brake and ESC (electric stability control) systems.

The resulting reduction in mechanical drag along with revisions to the existing S-tronic dual clutch gear box are said to provide prototype versions of the A4 2.0 TFSI quattro ultra with fuel savings of up to 0.3l/100km in everyday driving conditions.

To activate four-wheel drive, the multi-plate clutch closes to operate the propshaft. In doing so, it accelerates the gears in the rear differential. When they are running at a necessary speed, the claw clutch closes via pretensioned springs to provide drive to the rear wheels, at point which an electromagnetically actuated pin disengages a locking lever.  

All up, the quattro ultra system is claimed to weigh four kilograms less than the existing Torsen based quattro system.

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Comments
11

16 February 2016
Not sure I like this as it sounds like they are trying to turn torsen into haldex. If you drive a torsen Quattro in the snow it will be very sure footed under acceleration but with haldex the back end keeps stepping out as it dumps loads of power to the back in an unsubtle fashion when the front loses traction. Only one way to find out mind!

16 February 2016
Yet another non four wheel drive four wheel drive. No amount of jiggery pokery and millisecond technology will make a front wheel drive car four wheel drive car. You might as well buy a Honda CRV SUV.

Lanman

16 February 2016
Audi's proper 4wd system at least had some form of rearward bias to keep enthusiastic driver happy. Now we get a re-engineered haldex system which as everyone who has driven one will tell you is highly effective but numb and unentertaing. Progress through technology just got thoroughly out engineered by Ford and GKN, all in the name of efficiency. Dear Greenpeace/EU please let me have some fun at least once more before I die. As a current gen S5 owner i will see no reason to change for anything with the four rings on the front any time soon.

16 February 2016
[quote=mshinebaumDear Greenpeace/EU please let me have some fun at least once more before I die. [/quote] I don't think Greenpeace or the EU read this website very often, so you're probably best emailing them directly.

16 February 2016
Having had Quattro's since 1988 I would not buy an RS4 0r any other model without The Torsen system. Its a personal choice but I hate Haldex and Merc's 4matic. Can be so unpredictable when lifting off.

16 February 2016
This was Audi's opportunity to change the game and go for something like the Nissan GTR setup - rwd until 4wd is required. They could have become a genuine premium manufacturer in this segment, rather than one which is known only for good materials and construction, yet lacking the dynamism of Merc and BMW.Their rivals can rest easier knowing Audi will not be a true contender for the foreseeable future.

16 February 2016
Confused. This is called "quattro ultra" yet they're already selling ultra-labeled cars to mean their eco versions. Does that mean we'll get quattro ultra ultra 4-wheel drive eco cars?

16 February 2016
Won't pass judgment yet but not convinced. I needed a compact car with proper AWD because of snow and some fairly challenging off-roading. All the cute utes with FWD that shifted to 4WD were half-baked and didn't deliver as promised, so it had to be a Subaru Forester. It really can climb a hill with zero traction on one side.

16 February 2016
can you back-to-back test this with a comparable torsen quattro please? or, do a group test of the differing systems, even though the cars themselves are of different categories, just to see how they compare?

16 February 2016
Any nerds out there know how this compares to my xDrive? I was forced into xDrive for boring reasons and do miss my old sDrive on a good road. Also, given that these systems are computer controlled, when are we going to be able to take manual control over them eg set the system to FWD / RWD / Left-Wheel-Drive / Right-Wheel-Drive?!

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