What You Need to Know About Audi’s New Quattro Ultra All-Wheel Drive System

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Audi may not have invented all-wheel drive, but it’s safe to say the German automaker has pretty much perfected it over the years.

Introduced in 1980, Audi’s Quattro all-wheel drive has become as synonymous with the brand as its four-ring logo. Helping its cause is just how tremendously reliable the system has been, providing peace of mind and performance for almost four decades. And now the automaker is looking to add efficiency to that list, with a new all-wheel drive system dubbed Quattro Ultra that breaks from the norm and operates as a front-wheel drive setup first and foremost, with power heading rearwards only when needed.

“The idea is to improve fuel efficiency, and this is done by making sure the vehicle is in all-wheel drive when all-wheel drive is required,” said Rolf Kronstorfer, Audi’s head of advanced transmission engineering and all-wheel drive development. “But if all-wheel drive is not required, then we switch to front-wheel drive.”

AudiQuattroUltraAllWheelDrive

How it Works

Sounds simple, right? In theory, perhaps, but not in practice. Designing a drivetrain that functions in two manners, not to mention doing so completely independent of driver input, is no easy task. Complicating matters further is the system’s ability to work in both predictive and reactive fashions, analyzing inputs like steering angle, engine torque, acceleration and, of course, traction, to decide whether power should be delivered to all four wheels, or just the front two.

“The predictive strategy works by looking at different [data inputs],” Kronstorfer said. “It looks at how they are applied and which way they are applied. Additionally, it looks at vehicle speed, we look at engine rpm and which gear is chosen, and therefore we can predict the torque that we need to transfer to the street.”

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If the system justifies it, Quattro Ultra will send 100 percent of available power to the front wheels by disengaging the front clutch, located at the transmission, and a second one fitted inside the rear differential. When additional traction is needed — say, when driving on sand or loose gravel, or accelerating hard through a corner — both clutches are engaged, pushing a portion of that power rearwards.

The entire process of switching to all-wheel drive can be completed in about 200 milliseconds if needed, according to Kronstorfer, but the plan is to use the predictive strategy to make the decision before four-wheel traction is needed.

“The idea really to make sure that Quattro Ultra is driving like the [existing] Quattro system so that you never have the impression or the feeling that the car is sometimes in front-wheel drive and sometimes in all-wheel drive,” he said.

AudiQuattroUltraAllWheelDrive

Splitting Torque

When it comes to torque split, the ratio of power divided between the two sets of drive wheels, Quattro Ultra can send all of its power to the front wheels, but not vice versa. This, of course, is a result of the system’s ability to operate in front-wheel drive but not rear-wheel drive, though it can send the majority of the available power to the rear wheels under certain conditions.

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“If you only focus on static driving conditions, then every [system] has a maximum torque split of 50/50 because you can’t do more than lock it,” Kronstorfer said. “But if you focus on dynamic driving behavior — so, for example, accelerating — then you have a transfer of weight from the front of the car to the rear axle, and if you have more weight of the car on the rear axle you can transfer more torque. And then it automatically switches to 40/60 or 30/70 front/rear split.”

Saving Fuel

The main goal of Quattro Ultra is to reduce fuel consumption, something Audi claims it has proven — and not just in a controlled environment. According to the automaker, internal testing in live traffic scenarios in Germany found an average fuel consumption improvement of a little less than one mpg (0.3 L/100 km) compared to the same vehicle without Quattro Ultra. That may not seem like much, and probably benefits Audi’s emissions targets more than the average consumer, but every little bit helps. Crunching the numbers using the U.S. EPA’s fuel economy rating model, driving 15,000 miles annually would result in about two tanks worth of gas saved over the course of a year.

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But Does it Work?

First introduced on the 2017 Audi A4 Allroad wagon, the automaker is now ready for Quattro Ultra’s first true test: The 2018 Audi Q5. With the automaker launching a redesigned version of its best-selling vehicle, it has implemented Quattro Ultra in a model for the masses.

Driving the combination of twisting asphalt and gravel roads and sandy beaches of Mexico’s Baja California, Quattro Ultra was up to the task, providing impressive traction when needed. The Q5 has long been among the most surefooted premium crossovers on the market, and the dual-drive powertrain did nothing to change that.

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At the end of our day-long excursion, results tallied using a real-time analysis program proprietary to Audi showed one tester had 167 disconnects — the number of times the system switched out of all-wheel drive — resulting in 69 percent of the roughly 192-mile (308-kilometer) journey being completed in front-wheel drive.

But the key to the whole system is its imperceptibility, with Quattro Ultra making the transition between two- and four-wheel drive — and back again — without the driver noticing, something it delivered on during our time behind the wheel.

  • smartacus

    i see the point of two clutches on both ends of the rear driveshaft,
    but how does it send more than 50% of torque to the rear?

    is there a third clutch pack on the front differential?

  • smartacus

    and if they are concerned with dynamics;
    why not make them a front-mid engine layout,
    since they are awd anyway?

  • realposter

    I’m not enthused by this at all. Audi spent all these years taking weight off of the nose and pushing more torque toward the rear – only to completely switch back to save a tiny amount of fuel. Finally there is some more feedback now that the front wheels have less torque going to them… Finally you can feel the sensation of being pushed out of the corners. I don’t see how this setup can replicate that. As you siad – this sounds like their Haldex setup on the “lesser” Quattros. My currecnt Audi is 40/60 normal split and 15/85 at the max to the rear. You can tell the difference. I don’t think I will like this at all.

  • MXJ222

    If they use this on RS models, they might as well shut the doors on the Audi Sport division.

  • realposter

    Not just RS models. I drive an A4. If I wanted a FWD vehicle I would get a Camry. I bought this version of Quattro because of the rear biased torque split.

  • Bill Malcolm

    Exactly. They must roll out the bafflegabbers to talk pure rubbish to the assembled reporting horde like suggesting the system can do 40/60 or 30/70 f/r. Not possible because there is no third clutch attached to the front wheel drive part of the system. FWD is always connected. Not that the reporters, uh motoring scribblers waiting for prawn cocktails and beer, have a clue or they’d ask the very question you did.

    All this complication in Ultra Quattro to disconnect the propshaft and rear axles to maybe save 0.3 l/100 km in fuel.

    Other than that it’s the same Subaru MPT system that the Japanese company has had since 1988 on their cheaper automatic transmission cars. What Subaru managed to understand is that with tires on the ground rolling straight, they ensure that the “degree” of clamping of the front/rear clutch is completely immaterial. The clutch plates simply do not slip relative to each other because the wheel sizes are the same front to rear, rotate at the same speed, and there is thus no difference in speed between the clutch plates attached to the rear of the transmission, and those attached to the propshaft. No wear at all.

    Same situation if there is an actual centre differential. No differential action occurs if front and rear wheels are turning at the same speed – straight line condition.

    Only in a curve or when wheel slippage occurs will the clutch plates slip or diff gears (regular or planetary, it makes no odds) rotate over each other. These are transient conditions and the time when clutch plates wear, the extent depending on how hard they are clamped together by the system but still have to slip. The systems with geared centre diffs just act like gears and don’t wear at all.

    Subaru used to have a better AWD system called VTD for automatics that had a gear centre diff they put in their more expensive cars. I have one on my 2008 Legacy GT auto. They abandoned it for 2016 on all models without a word, although early 2015 WRX autos and the six cylinders still had it. It’s more expensive to make, and is identical in mechanical operation to the quattro still being fitted to everything Audi but this Alltrack thing. They both feature planetary gear differentials to give whatever the so called static torque split is that virtually never occurs in practice. Plus VTD had an electromechanical-operated variable clamping force clutch LSD on the centre diff, like later quattros (Subaru’s came out in 1992! on SVX’s sold outside North America). A special version of it in two separate series have always been on the STI.

    Only VW/Audi would bring out a cheaper clutchpack AWD than their regular system and then deliver highly slanted and misleading BS that it was better. Fake news. They just say that so when they shave a couple hundred bucks off manufacturing cost and shove this system in all their cars, everyone will already have swallowed the pill that eww Ultra Quattro is better. It ain’t. And it’s obviously not full time AWD like even Subaru’s cheap MPT system – no, you have to wait while “predictive” sensors hook up the propshaft and then rear axle. 150 milliseconds. Instead of zero time for regular quattro or the Subie system. Oops! Black ice on the curve – how’s the prediction, Hans?

    Sometimes I just get mad at the way different AWD systems are described, especially when PR guys are on the prowl. The systems just aren’t that complicated, but everyone acts as if it were black magic. You can tell an overawed public anything, feed ’em any old “explanation”, watch their eyes roll back into their head, and you’ve got them where you want them, and can mislead to your heart’s content. I’m led to believe the approach works in politics as well. But here, as a mechanical engineer, I’d say Ultra Quattro is just a bunch of squeezed lemons being sold as fine wine.

  • Bill Malcolm

    You have to have actual wheel slip front to rear to get anything other than 50/50. The tires guarantee it. Or on a curve, when by definition, front and rear axle speeds differ. Those are the only two ways to get different front and rear wheel speeds, when the planetary centre diff actually does anything other than turn at the same rate as the front and rear propshafts. Same on my Subaru VTD, but instead of using a Torsen centre-diff, it uses a variable clamping clutch limited slip on the centre diff. I had a ’94 quattro from new with the Torsen centre diff before they stuck the planetary feature on it to give the so-called 40/60 torque split. It was the most stable AWD system I’ve ever experienced in slush – virtually zero clawing and grabbing.

  • realposter

    The current Audi’s don’t use Torsen… Many people don’t realize it. When they moved to the 40/60 they had their own self locking center diff… Then they developed a crown gear which was smaller and lighter (seems to be only on RS vehicles though).. As to stable in the bad weather – yes I can believe the older system was somewhat more capable. But those older systems didn’t work as well side to side (unless you had one with EDL). That said – the newer Quattro with the 40/60 split are still more stable in snow/ice than many systems I’ve experienced in SUV’s for example. That said – I live where it snows maybe 10 times a year – not 50.. So in my case I will trade slightly less snow/ice stability (still quite capable) for the normal everyday feel of more torque going to the rear. The maximum split is 15/85. There have been times where I have felt is – or close to it – accelerating out of a corner. It’s a fun feeling. That said – this “ultra” – Haldex type system doesn’t seem like it will be as capable in the snow/ice – nor as fun to drive. This seems it’s just to save a few pounds to meet fuel economy standards. For the small savings it doesn’t seem worth it. Most AWD systems now are trying to be as light as possible. Some are “fully variable”. Most electric vehicles in the future will probably all use AWD – since there will be no weight penalty… A system that used FWD as it’s default will defeat all the work Audi has done in recent times to make it’s vehicles more engaging.

  • AND YOU ARE A FAKE NEWS BULLSHIT!