Greetings, my regular subscribers and readers! As you already understood, the principle of operation of this technology and its features are on the agenda of the quattro all-wheel drive.
True Audi fans know that you can only experience the thrill of driving these German cars with quattro drive. Among the main advantages, they, of course, will name dynamics, controllability, maneuverability and will say many more laudatory words.
But is this really true or is it just another marketing myth? Let's figure it out.
Engineers from Ingolstadt introduced the drive called quattro back in 1980, and, of course, to this day it has been repeatedly modernized and transformed - there are about five major stages in its history.
Despite the inevitable technological progress, the basic chips of this technology from Audi have always remained unchanged - this is a permanent all-wheel drive system with a longitudinally mounted engine.
We emphasize once again - permanent all-wheel drive and longitudinal units. Due to the fact that the car, regardless of the situation, all four wheels are leading, it was possible to achieve unique stability on any road surface, high efficiency from engine braking and enviable handling.
What was invented in Ingolstadt?
Why has quattro become such a desirable system for many car enthusiasts? It's all about the German approach to engineering - these guys know how to hone any technology to a shine.
Well, let's see what's inside the all-wheel drive Audi.
First of all, it must be said that quattro can use both a manual gearbox and an automatic one, and the layout of the drive can also vary depending on the model. But be that as it may, the main elements of the system are always:
- Transmission;
- razdatka (transfer case);
- cardan transmission;
- main gear;
- cross-axle differentials available on each axle.
As we have already said, gearboxes can be installed in a variety of ways, but in our case there is one design feature - the gearbox is mechanically combined with a transfer case, which redistributes the engine torque along the axles.
In recent years, Audi engineers have gone even further and shoved into one body not only the gearbox and transfer case, but also the front axle drive shaft, final drive, and also the cross-axle differential in addition.
Separately, it is necessary to mention the center differential, which is also hidden in this case.
With the development of the quattro system, it changed from a primitive one with a mechanical lock to a more advanced Torsen, a technically sophisticated self-locking one with crown gears, capable of changing the redistribution of torque along the axes depending on the driving mode in addition to everything.
Rotation to the front axle, as already mentioned in passing, is transmitted from the transfer case by a shaft to the main gear and differential.
The rear axle gets the torque through the driveline. Structurally, it is made of two shafts, an intermediate support and three hinges of equal angular velocities. The cardan rests against the rear axle, where, as a rule, the main gear and another cross-axle differential are located in the hotel building. By the way, it can be free with a mechanical or electronic lock, and sometimes with a self-locking Torsen.
Watch this video, everything is clear here how quattro works:
I must say that not all four-wheel drive Audis can boast of permanent all-wheel drive. So, for example, models with a transverse motor are equipped with an automatically connected system with a Haldex coupling. Probably, connoisseurs have already realized that such technology is nothing more than a 4Motion drive from Volkswagen.
Ecology and four driving wheels
And in conclusion, friends, a few words about green technologies. Yes, yes, we remembered them in the context of this article for good reason. The fact is that a few years ago, the craftsmen from Audi developed a hybrid all-wheel drive, called the E-tron quattro.
It is organized as follows: the front wheels are rotated by a traditional internal combustion engine, but the rear axle is driven by electric motors. Such is the progress.
See you soon, fellow motorists! Let's explore cars together!
Not so long ago, our expert Boris Ignashin wrote a rather detailed material about why, in principle, it is needed. Here we will focus on the technical and philosophical differences between the famous 4x4 systems, but briefly, nevertheless, we will explain what is the meaning of this disgrace.
The most obvious "passenger" advantage of an all-wheel drive transmission is better accelerating dynamics: it is clear that the car accelerates faster if the torque is transmitted to all wheels, and not just to one pair. This is especially noticeable on slippery surfaces and with excess power: for some sports cars with modifications with different types of drive, even the passport acceleration time to 100 km / h is less for the 4X4 versions. But still, each wheel has a certain limit of adhesion, and if during rectilinear movement it limits only the magnitude of the realized moment, then in a turn everything is somewhat more complicated.
Here the load on the drive wheel is the sum of the longitudinal force, that is, the thrust vector, and the transverse force, which tends to move the car outward from the center of the arc - when the sum of these forces exceeds the specified limit, slipping begins. That is, a wheel loaded with torque resists side load worse - which is why, in the general case, rear-wheel drive cars have oversteer (the tendency to skid the rear axle), and front-wheel drive cars are insufficient (demolition of the front wheels). In practice, there are exceptions to this rule, due to different distribution of mass along the axes and other factors, but the problem exists, as well as the solution - all-wheel drive.
However, here, too, everything is not so simple, and in the literal sense of the word. If a two-wheel drive car is not a mystery for a more or less qualified and experienced driver, then when going into a fast corner with all-wheel drive, you need to be prepared for both drift and skid, not to mention the slip of all four wheels, and one phase can instantly change to another.
Such waywardness manifested itself in one of the first production all-wheel drive cars Jensen FF, which was released back in the 60s of the last century. Automotive journalists admired the phenomenal stability of the British sports car (by the way, its engine power exceeded 300 hp) on wet roads, but noted that when it reaches the limit, it breaks down sharply and unpredictably, and it is very difficult to “catch” it. Since then, for half a century now, designers have been struggling to create all-wheel drive without fear and reproach not for off-road, and, of course, there are certain successes.
Quattro and the Germans
The first truly successful "passenger" all-wheel drive system is considered to be the famous quattro from Audi (we wrote in great detail), first tested in rallies (and it is precisely because of this that it is so "hyped"), and since 1981 it has been used on "commodity" cars. Meanwhile, at first, in some ways, this transmission was even more primitive than that of the same "Jensen" fifteen years ago.
The British already then used a self-locking center differential of the original design, and asymmetrical. At Audi, the thrust was distributed between the axles in a ratio of 50:50, and the role of the "center" was played by an ordinary planetary differential, forcibly blocked by the driver, approximately like our "Niva".
The merit of the Germans was different: they very competently arranged their transmission, ideally adapting it to the traditional "audio" scheme - initially front-wheel drive and a longitudinal arrangement of the power unit. As for advanced solutions, they did not have to wait long: after a few years, the aforementioned Torsen mechanical “self-blocking” was already in charge of the distribution of traction, instantly and smoothly responding to changing traffic conditions.
However, the habits of all-wheel drive Audi still gravitated towards front-wheel drive: in order to overcome understeer, the car had to be “broken” like a rally at the entrance to the turn by decisive actions with the steering wheel or accelerator pedal. Of course, we are talking about extreme driving, in normal modes the cars kept the road perfectly and willingly fit into turns, but still ...
And in 2007, Torsen became asymmetric: "by default" he distributed torque in a ratio of 40:60 in favor of the rear wheels, and if necessary, they could receive up to 80 percent of traction. At the same time, the weight distribution of the new models was revised: if earlier the designers tried to load the front drive wheels as much as possible, now, for the sake of controllability, the emphasis was on the rear ones.
As a result, the quattro system undoubtedly won, but, for example, the A4 model, deprived of it "in the base", became "non-wheel drive": a sharp start on its initial front-wheel drive version is very problematic due to insufficient loading of the front end. In fairness, it should be noted that the “younger” Audi A3 avoided a similar fate, since it is based on the Volkswagen Golf platform with a transverse engine, and the quattro philosophy is completely different here, based on a permanent front-wheel drive and an automatically connected rear with a Haldex friction clutch.
Such electronically controlled clutches, only in front-wheel drive, are used by BMW today in its xDrive transmission. True, the Bavarians did not come to this immediately: from 1985 until the end of the 90s, they used blocking of the interaxle and rear interwheel differentials with the help of viscous couplings, then they were replaced by electro-hydraulic clutches, and at the turn of the century, relatively short experiments were carried out with free differentials and electronic emulation of interlocks (brakes "grab" slipping wheels, redistributing traction to the rest).
Today it is kept at the cross-wheel level, and the cross-axle clutch works in close cooperation with electronic security systems that monitor a lot of different parameters and give a signal to the degree of compression of the friction discs. This xDrive is fundamentally different from quattro, where the lock is mechanical, but, unlike Audi, all-wheel drive BMWs can turn into pure rear-wheel drive if necessary, which is sometimes very good.
And what about the third member of the big German troika? For more than fifteen years, Mercedes has remained true to the 4Matic concept, first embodied in 1997 in the transmission of the M-class crossover: free differentials (center - with a slight "rear-wheel drive" accent) and no locks, only their imitation with the help of brakes. But the imitation is very convincing: if at least one wheel maintains reliable contact with the surface, the car is able to move, and on a slippery road, smart electronics deftly juggles traction, avoiding both understeer and oversteer.
Meanwhile, Firmatik began in 1986 with a very sophisticated scheme for those times: the all-wheel drive E-class sedan had as many as three fluid couplings that automatically connected the drive to the front wheels, and then blocked the center and rear center differentials.
The transmission of the Porsche 959 supercar, the serial version of which was released in the same 1986, had a similar design, with the only difference that it had an engine located at the back, and an extremely advanced computer for its time was in charge of blocking the “center”. The current all-wheel drive Porsches have, of course, more powerful brains, but the essence is the same: electronics, in close cooperation with security systems, control the multi-plate clutch in the front wheel drive, much like a BMW.
Pictured: Porsche 959
Asian response
In Japan, the relatively small company Fuji Heavy Industries, which produces cars under the Subaru brand, is considered a pioneer in the widespread use of all-wheel drive in passenger cars. At first, in the 70s, they were distinguished by a clear off-road bias, but the scheme of the famous symmetrical all-wheel drive gradually crystallized, obviously not without the influence of Audi.
It is related to the quattro concept by the longitudinal engine layout, and the basic front-wheel drive, and many variations that have arisen in the course of evolution - but, unlike the Germans, the Japanese still moved away from the idea of \u200b\u200b"honest" permanent 4WD: recently, cars with "automatic" uses the clutch of the automatic connection of the rear axle.
However, this did not prevent the Subarovtsy from creating a real legend: in 1992, the Impreza model debuted, created on a shortened Legacy platform specifically with an eye to participating in rallies (another parallel with the Audi quattro). The civilian version of the sports car received the designation WRX and the most powerful version of the STI, which quickly gained the status of a cult car for fans of active drive. The guarantor of this was a transmission with differential locks, where viscous couplings were used in different generations, and the same Torsen, and the current STI has a design called DCCD (Driver Control Central Differential) between the axles, capable of changing the degree of blocking both independently and at will driver.
In the photo: Subaru Impreza
The eternal rival of the sports "Impreza" - Mitsubishi Lancer Evolution, which started in the same 1992 and has now survived the tenth generational change. The main difference from Subaru is the transverse engine, everything else is similar: permanent four-wheel drive, where the "center" was initially blocked by a viscous coupling, and now this function is assigned to electronics.
But Mitsubishi's main trump card is the AYC (Active Yaw Control) rear differential developed back in 1996 and improved: it does not just block, but changes the final gear ratio for each of the wheels separately using a gearbox, "twisting" one of them in a turn, which carries a large load. In the latest version, the driver can select different transmission modes, depending on which the car drives in different ways: either very quickly and safely, following a given trajectory, or in a hooligan way, allowing you to easily control the skid. Not surprisingly, many experts call the current EVO the world's best "driver" car among relatively inexpensive ones, and the Japanese company's recent decision to discontinue its production plunged fans into gloom.
However, something similar can be experienced behind the wheel of a much more budget "Japanese", Nissan Juke - of course, in the all-wheel drive version. Its transmission, of course, is simpler, but it has its own zest: the rear wheel drive uses not one friction clutch, but two, its own for each wheel, and all the same ubiquitous electronics can theoretically transmit traction, for example, only to the right side.
In practice, this translates into a very effective weapon against understeer, and such a Juke copes with hanging wheels very well - however, the latter refers to cross-country ability, and we are talking about "drive". And here Nissan has another outstanding achievement in the face of the GT-R supercar, notable not so much for the type of all-wheel drive (between the axles - a multi-plate clutch, at the back - a mechanical "self-block"), but for the original layout.
With a front-mounted engine, its gearbox is moved to the rear wheels for better weight distribution (the so-called transaxle scheme), so one cardan shaft goes to it, and another, almost the same length, to drive the front wheels, runs parallel to it in the opposite direction. On what only tricks you will not go for the sake of speed and driving pleasure!
Of course, the list of various all-wheel drive systems used by Japanese manufacturers is not exhausted by the given examples: for the domestic market, many passenger models that we receive in the front-wheel drive incarnation are produced in 4x4 modifications that are outlandish for us.
Although in Russia, for example, not so long ago it was possible to purchase a Honda Legend sedan with an intelligent drive that distributed power, again, individually for each wheel (later this system was abandoned due to the high cost). But almost all transmissions are variations of the described schemes, and the differences lie mainly in the design of the locking mechanisms: it can be an electric drive or hydraulics, and someone still has good old viscous couplings in use. The general trend is the ever wider use of electronics, the complexity and settings of which today depend almost more than on the mechanical component.
On the picture: Mitsubishi Lancer Evolution 1992
What's next?
The emergence of hybrid all-wheel drive systems, including electric motors, can be considered a logical continuation of progress in this area. After all, there is no need to pull any cardans, providing for them tunnels that "eat up" the internal space: you laid the wires - and you're done.
By the way, one of the first all-wheel drive vehicles in the world was built more than 100 years ago by the then very young Ferdinand Porsche, and it was precisely an electric car with four motors, one for each wheel. Since then, both electric motors and batteries have become much more efficient, and the French have succeeded more than others in this matter.
In particular, Peugeot already has two production models, 508 and 3008, which have versions where the front wheels are rotated by an internal combustion engine, and the rear wheels are synchronized with an electric motor of relatively low power, but with huge torque available at any speed. So far, such hybrids are aimed more at fuel economy and environmental friendliness than at driver values, but, as they say, it's a start.
The all-wheel drive system, developed by the German manufacturer Audi, has come a long way, which began with a small military vehicle Iltis, assembled by Volkswagen developers. She quickly improved and very soon left all her relatives far behind, firmly taking a leadership position. Even many rally aces have preferred the Quattro over many other models.
Below we consider the most famous all-wheel drive cars from Germany, which have become legends in automotive history. But before that, let's get acquainted with the undeniable advantages of the system, as well as some of its shortcomings.
Advantages and disadvantages of cars equipped with all-wheel drive
So, here are the main advantages of Audi all-wheel drive models:
- high cross-country ability;
- regardless of the condition of the road surface, the start of movement and acceleration take place at good acceleration without unwanted slipping;
- sensitive handling;
- swiftness and stability;
- effective engine braking.
Cars Audi all wheel drive have some flaws:
- higher fuel consumption;
- car prices are much higher;
- in the event of extreme situations, you can abruptly and unexpectedly lose directional stability and control if you do not have good driving skills;
- structural complexity, which entails a rather expensive and time-consuming repair.
Overview of popular Audi car models: Quattro all-wheel drive
Audi Quattro Coupe
The Quattro Coupe has an elegant look, which is formed by thin pillars and small wheels. It is equipped with a turbocharged five-cylinder engine with good power and torque. The car is able to accelerate in just 7 seconds. Its maximum speed is 220 kilometers per hour. The car has excellent grip.
The steering is light and slow, but at the same time quite informative. The steering wheel is attractive because you can create the perfect effort on it, giving a certain sense of confidence.
Audi Sport Quattro
Audi Sport has become a kind of extreme solution for developers. She acquired a shorter wheelbase, her weight was 1.2 tons with a power of 302 liters. With. The car can accelerate from standstill in just 4.8 seconds to 100 kilometers. It became the greatest representative of a rally-directed car in the history of its manufacturer. Its distinctive features are “nostrils” in the hood for additional air intake and “gills” in the wings for fuel removal.
The steering is quite heavy, but responsive. The clutch and propulsion system are characterized by a certain rigidity. When cornering, there is no roll, the steering wheel is very informative. Manoeuvres, the car performs willingly and easily, with a change in balance, based on the level of opening of the damper and the work of the brake pedal.
Audi RS4 Avant
This model Audi equipped with all-wheel drive system combines classic features with modern ones. It is compact and straight, has good visibility and excellent build quality. A distinctive feature is the most powerful eight-cylinder engine, which develops a fairly high speed in a matter of seconds.
The RS4 has good suspension, roll control, an advanced hydraulic system that is able to stabilize the body position during cornering maneuvers without disturbing the overall balance. The car has a certain plasticity and excellent control on the road. The steering is light, but absolutely confident.
Audi all-wheel drive cars are perfect for lovers of high speeds, and at the same time safe driving, lovers of travel and outdoor activities. Such a car will be able to emphasize your ideal style and solidity.
Four-wheel drive vehicles are the passion of many lovers of quality vehicles. We often dream that our car has enough performance to overcome difficult obstacles, off-road or terrible road conditions. Today, each company has its own technologies for implementing all-wheel drive in crossovers and SUVs, but not all implementations turn out to be really high-quality and convenient. In today's publication, we will consider the possibilities of two popular German technologies from the same concern. Quattro all-wheel drive is used in Audi cars, and 4Motion technology adorns the complete set of Volkswagen cars. Despite the closeness of these two drive options, they also have certain differences.
Experts will say that comparing these systems does not make much sense, especially if we are talking about the importance of all-wheel drive in a car. All four-wheel drive systems at Volkswagen AG have similar characteristics and are based on Torsen or Haldex couplings. In fact, these systems differ only in names, so it makes no sense to compare them. Comparing these two all-wheel drive options makes sense with systems from other manufacturers. However, many modern 4WD or AWD systems are made according to this scheme.
What is the difference between Quattro, 4Motion and other technologies?
By and large, there are no technical differences between the various all-wheel drive systems. The manufacturer calls the Quattro and 4Motion systems permanent all-wheel drive, but in reality this is not the case. The clutch starts to work only in those situations when the car experiences certain difficulties with movement. Otherwise, all-wheel drive works very poorly, it is not felt at all on the track. And in this case, it makes no sense to compare the two types of all-wheel drive. Successful solutions are based on the following features of these elastic systems:
- a certain set of settings for controlling all-wheel drive is adjusted for each car;
- the drive turns out to be quite elastic, it is not designed to overcome obstacles, but only adds to the impressions of the trip;
- 4Motion and Quattro are connected safely, the car does not jerk when torque is applied to all wheels;
- the clutch is very reliable, during the life of the car you are unlikely to have to repair the all-wheel drive system;
- emotions from driving a car with such systems are very colorful, transport surprises with its handling;
- you do not have to manage the four-wheel drive through various manual settings - everything is done automatically.
There is no need to learn how to drive a car with an all-wheel drive system. You can simply use the car for its intended purpose and not think about technical details. But these many do not like the Quattro and 4Motion all-wheel drive. After all, sometimes you want to feel the difference, and sometimes just turn off one bridge and save fuel. But there are no such functions in these systems. All-wheel drive from Volkswagen AG is surprisingly technological and high-quality, but it is not suitable for a professional driver or racer who wants to feel all the subtleties of the car's behavior on his own.
Comparison of all-wheel drive Volkswagen with other manufacturers
The only comparison that makes sense in this case is comparing Quattro and 4Motion all-wheel drive with Subaru technologies. Japanese all-wheel drive technology has been developed to incredible heights, with the legendary Subaru system receiving the award for the best all-wheel drive systems every year. But not all cars of the concern have this legendary four-wheel drive. There are many trim levels with the usual Full Time 4WD, the same performance as the Volkswagen. However, basic all-wheel drive on expensive cars is exactly proprietary technology with the following important advantages:
- the possibility of manual control of the high-quality functions of the all-wheel drive of the car;
- full control and fine-tuning of the operation of transport in a particular case and in different driving conditions;
- an incredibly sensitive clutch that has all the necessary locks, everything is implemented in the mechanical part;
- no electronic imitations of control and blocking, everything works according to traditional technologies;
- lack of weak points that could break after several years of operation.
Unlike Subaru, Volkswagen's all-wheel-drive cars don't have the same interesting features. This leads to the fact that users of German-made cars do not always remember what functionality is present in their car. Given all the features of Japanese technology, if you want a car with good control functions, you should give preference to the Japanese. But in case you are satisfied with the lack of a mass of adjustments and settings, it is better to buy a German car.
Novelties and development of German all-wheel drive technology
Given the fact that all manufacturers in Europe and China follow the example of Quattro and 4Motion, the company is constantly improving its technologies. Successful solutions in all respects annually supplement the technical base of cars produced. It is quality and functionality that become the main changeable functions. The concern introduces new interesting technologies that allow you to keep the car on the track at high speed, reduce the feeling of being squeezed into the seat when accelerating, and also serve to perform other important tasks:
- lack of weaknesses and repair of childhood diseases of the all-wheel drive system and computer control function;
- improvement of the gearbox, which is the main device in the transmission system;
- reducing the effect of connecting all-wheel drive in the presence of such an automatic function;
- increasing the comfort of the trip and the implementation of behaviors unusual for a powerful car;
- integration of new technical units developed directly by the engineers of the German company;
- reducing the cost of implementing the all-wheel drive design and facilitating all elements of this system.
Reducing the weight of the machine has become a real object of pursuit for modern manufacturers. Also, the German concern is strongly focused on reducing fuel consumption. Therefore, the company offers customers constantly new and new technologies for the implementation of a variety of solutions. In particular, four-wheel drive used to be a factor in increasing consumption, but today 4Motion and Quattro have little to no effect on consumption. A few percent increase appears only due to the greater weight of the car. And such subtleties inspire a certain confidence in new developments, despite their high cost for the company. However, the price of cars has long ceased to rise actively. This is how you can drive this four-wheel drive, if you know how to really drive a car:
Summing up
Four-wheel drive based on German Quattro and 4Motion technologies is a completely adequate system for an ordinary passenger car. But if a full-fledged large SUV was present in the manufacturer’s model line, such a system would look pretty ridiculous on it. The corporation has repeatedly worked on the creation of a classic mechanical all-wheel drive, but all developments ended with the fact that the integration of the invented systems into cars looked pointless. Unless Amarok could claim to get a more efficient all-wheel drive system, but this is not a car in which the buyer agrees to pay for such developments.
Therefore, for Volkswagen, the existing technologies of a simple but confident all-wheel drive remain the only and optimal ones. Every year they are refined, changed and receive certain minor updates. But this is no longer so important, because the technology remains the same, the principle of operation does not change. If you are interested in the technical part of the car's all-wheel drive, it is better to ask your questions to the manager in the cabin, who should know the pros and cons of this drive option, as well as compare with the main competitors. How do you feel about amateur all-wheel drive systems like 4Motion and Quattro?
Audi has decided to ditch all-wheel drive with a Torsen center differential on most of its models. It is being replaced by a new design, radically different from its predecessor. "Motor" attended the presentation of the novelty, carefully studied it and tested it on public roads.
####What's happened?
Audi has introduced a new all-wheel drive design called quattro ultra. It will be used on cars with a longitudinal engine and can be combined with a manual transmission or with a robotic S tronic. Simply put, the quattro ultra system is for everything built on the MLB modular chassis. That is, for the entire A4 family, the first model with quattro ultra will be the new generation A4 Allroad, as well as the next generations A5, Q5 and A6.
The key difference between the new system and the current one is the replacement of the asymmetrical Torsen center differential with an electronically controlled Magna clutch, the disks of which are in an oil bath (five or seven pairs, depending on the model and engine power). At the same time, the location of the clutch is the same as that of the Torsen - immediately behind the gearbox.
But that's not all. In quattro ultra there is another clutch, a disconnect, which is located between the right rear axle shaft and the rear differential housing. It is cam, and its main task is to open when no torque is supplied to the rear wheels. In this case, the rear wheels will rotate freely, and the driven and driving gears of the differential will not rotate at all: only satellites and axle gears rotate freely around their axes.
In a situation where the front clutch closes and begins to supply torque to the rear wheels, the rear clutch closes under the action of a spring and all four wheels begin to rotate together.
####And if it's simpler?
It's simple: earlier on the Audi A4 there was a permanent all-wheel drive with a mechanical self-block, and now it is connected with constantly paddling front wheels.
####What was wrong with the old four-wheel drive?
The new system has several advantages. First, it helps to reduce fuel consumption. Let it be insignificant - only by 0.3 liters per hundred kilometers, but reduce it. This was achieved by reducing friction losses. Because when the dog clutch opens, the rotation of the largest component of the differential and driveshaft stops.
True, Audi experts recorded a difference of 0.3 liters during road tests in Ingolstadt, where traffic intensity, as well as the number of cars, is difficult to compare with Moscow traffic.
Secondly, the new system is lighter than the old one, with a Torsen differential. The savings are not the most significant - only about four kilograms, but still. The third benefit is the ability to control the distribution of torque along the axes more flexibly - after all, the electronic clutch allows you to direct any amount of torque to the rear wheels, from 0 to 100 percent.
####And how does it all work live?
According to Florian Kebl, head of the quattro ultra project, one of the developers' goals was that the driver would not feel the difference between the old design and the new one. And they seem to have succeeded.
In Austrian cities with inhumane speed limits and on the serpentines around Innsbruck, where endless bunches of turns do not allow acceleration, we managed to ride the latest generation A4 station wagon with both Torsen and quattro ultra. The “four” with a conventional central differential rides as neutrally as the laws of physics allow, and it is almost impossible to track how the diff changes the distribution of torque between the axles.
A turn of the steering wheel, a little more gas and the 4.7-meter wagon is screwed into the turn like a top. And while the passengers are remembering the safe word that you never came up with, the driver wants to move the bar of reasonable further and further, only occasionally fighting with the snout trying to slip out.
A car with quattro ultra drives in similar conditions... exactly the same. There is no difference in behavior or handling. Wagon writes the trajectory is very neutral. And the similarity is confirmed not only by the sensations behind the wheel, but also by telemetry. On the 60-kilometer test route, torque was applied to the rear wheels, in one amount or another, 70.8 percent of the time. Moreover, regardless of which mechatronic chassis mode was selected.
It takes no more than 0.2 seconds to connect the rear axle for cars with quattro ultra. Moreover, the rear axle is connected even before the front wheels begin to slip - the control unit receives data from the stabilization system, the control electronics of the power unit, analyzes the position of the gas pedal, engine speed and the coefficient of adhesion of the wheels to the road a hundred times per second. Even the presence of a trailer and driving style are taken into account!
In addition, the algorithm changes depending on which mode is selected in the drive select system. For example, in economical efficiency, traction is applied to the rear wheels less frequently, while in sporty dynamic, almost constantly. When starting from a standstill with dynamic mode activated, the rear wheels will work immediately, and not when the front wheels lose traction.
The similarity in the behavior of cars with Torsen and quattro ultra can also be explained by the fact that the distribution of traction between the wheels in both cases is in charge of the brakes: the inner wheels in the turn receive brake impulses that help the car stay on the path.
####So everything is cool?
How to say. It didn't get worse for the average driver. On the contrary, solid pluses: more understandable behavior on the road and lower fuel consumption. Whether the novelty will appeal to lovers of active driving, especially in winter, is a question that requires testing in more suitable conditions than licked Austrian roads.
