Hans-Dieter Seufert All-wheel drive systems put to the test
12.12.2010
It caught him overnight. The Porsche 911 Turbo was not immune to the freezing cold. Minus 20 degrees have bothered him. He has a cold. At least it looks like he's running his nose. Long icicles grow under the rear nostrils, frost crystals sugar the dark blue stature. Not exactly a heartwarming sight.
Here, imperial weather beckons. The over 3,000 meter high Wurmkogel is already burning brightly in the sunlight, while the crowd of ten all-wheel drive specialists are still laboriously shaking the cold out of their mechanics. But you need to warm up before you leave the base camp in Hochgurgl.
Grip is king in the all-wheel drive system comparison test
The snow crunches nastily as the shivering field opens up to the meeting point at 2,171 meters. On the five-percent incline to the Timmelsjoch toll station, the motley, traction-hungry troop must show what is hidden in the shallows of their respective drive trains. Grip is king. Up front is whoever rams the sipes of his winter tires into the piste when accelerating to 80 km /h.
The tires tip the scales when starting with and without ESP. Ingenious top performance fizzles out if the tires do not understand how to implement the most complex all-wheel drive systems. However, the mounted tires are part of the overall concept. Brand and specification exactly reflect what the customer gets assembled from the factory.
Even without ESP, the Mercedes GLK 350 successfully climbs the climb
So welcome to reality. The warm-up lap is over, on to the alpine glow that the Mercedes GLK 350 tackles first. The smallest SUV with the star meter makes it loose and unspectacular. Thanks to the finely timed ESP, it laces straight up. A lamella lock between the two axles regulates the traction and distributes a maximum of 70 percent of the drive force forwards or backwards. Even without ESP, the ascent succeeds without airs, with negligibly small course corrections. When braking on a slight slope, the measuring system confirms 50 meters.
A first guideline for the deceleration from 60 km /h to zero for internal competition. In terms of traction, the same system operates in the Mercedes E-Class 4-matic. Nevertheless, the diesel sedan (E 350 CDI) rolls off more impressively. It remains as stubborn as an S-BahnMercedes E-Class on course. Without ESP, the stern jerks only for the first ten meters, then the system is quiet. As is the case with the subsequent downhill, where the sedan effortlessly brakes. Safe is safe, what else could you expect from a Mercedes during the standard exercises?
Subaru Outback 3.6 R nests in the Mercedes environment
One out of three Japanese agrees. The Subaru Outback 3.6 R decelerates calmly and calmly on the downhill section, and with its objective performance it nests in the Mercedes environment. The same applies to the uphill stage, which the Nippon station wagon is a little less stable, but climbs with similar traction. The performance is not surprising, after all, a planetary gear set also ensures a predefined power distribution of 45 to 55 percent in the outback. And an upstream lamellar lock varies the power flow to the slower rotating axis, depending on the situation.
Without ESP, the Opel Insignia OPC prances nervously
Most of the protagonists who are still crouching in front of the slope trust the capabilities of an electrohydraulically or magnetically actuated multi-plate clutch. On the Opel Insignia OPC, the system is integrated in the housing of the rear axle differential.
If you move the Opel in dry conditions, it usually drives as a front-wheel drive, but lets the cardan shaft rotate at all times. If there is a difference in slip, the multi-plate clutch regulates within 80 milliseconds. But that doesn't change the fact that the OPC nervously prances tackles the climb without ESP, repeatedly demands steering corrections and a relatively large part of the power evaporates in slip.
Mitsubishi Lancer Evolution playfully wags from left to right
Even the Audi S4, which is comparable in terms of performance data, does not start much better at first. Without the very finely intervening ESP, the Quattro scrapes its wheels up to 50 km /h and wraps itself in a glittering white cloud. With increasing speed, the only one in the field who has a mechanical Torsen center differential can do a lot of meters and shines with impressive traction.
Only the Mitsubishi Lancer Evolution wobbles in front of the Audi when it sprints. But in the truest sense of the word, because without ESP, the rear of the rally base, which also has a mechanical front axle lock, can only be appeased with a lot of effort.
Nissan GT-R treats itself to the entire width of the road
There are still wilder dogs, the Nissan GT-R for example. He throws a lot of high tech into battle, but still treats himself to the full width of the street and a little more to storm the summit cross. The beefy force sets too harshlyone. Less is more on this track, which is expressed in the fact that the Nissan with the stability system starts much faster than without - at least over a second.
In the second parade athlete, the weapons are similarly blunted. The Porsche 911 Turbo remains more stable and fights its way up the hill in a more controlled manner. But it cannot generate convincing traction either. The power can only be converted into propulsion with great feeling, usually evaporates in the white. And that despite the rear axle lock and multi-plate clutch, which can transfer a maximum of 400 of the total of 650 Newton meters of torque to the front.
The forces of the BMW X1 are distributed quickly and imperceptibly.
The BMW X1 writes in the snow how it works with significantly less effort and construction effort. He uses a basic interpretation of 40 to 60 percent. An electronically controlled multi-plate clutch regulates the traction torques in question. The forces are distributed quickly and imperceptibly. The ESP only intervenes slightly. Even when electronically unleashed, the BMW X1 crawls up in a straight line. But down again, the performance is mediocre: the brake test fails.
The raging masses of the BMW X6 are difficult to control
Even the massive BMW X6 M decelerates better, if not brilliantly. Uphill, the 555 hp and 680 Newton meters trample the hill mercilessly flat. However, it is only advisable for experts to let the powers run wild. Because the gently intervening ESP automatically doses the power to a useful level and thus keeps the nervous BMW X6 safely on track.
Free from electronic constraints, the giant in the snow goes his own way. Once set in motion, the raging masses of the BMW X6 are difficult to control again. The warhorse needs the full width of the 780 meter long handling course. Only those who steer with foresight and accelerate will not torpedo themselves broadly into the boundary walls.
The x-Drive system, which has torque vectoring on the rear axle in the BMW X6, has basically no meanness up its sleeve. The selective distribution of power in the rear ensures neutral self-steering behavior. Pilots who still have an eye for it can even follow the flow of power on the navigation screen.
In fact, a lot of steering wheel action is required while the BMW X6 M V8 chants and flips over all four wheels. When the white spray subsides again, the handling test opened with a respectable time. Objectively, the little brother can do the BMW X6 not hold a candle to it. Subjectively, the BMW X1 but as a reliable partner for slippery surfaces. Fine thrusts lure the compact SUV from its understeering self-steering behavior. There is no lack of controllability and traction.
Subaru operates far below the driving pleasure scale
The Mercedes GLK again. Of course, the driving pleasure is less because the Mercedes takes the selective course under the wheels with a pronounced tendency to understeer. What applies to drought also applies to snow: safety first. This also means that the ESP is always present in an emergency.
Even further down the driving fun scale, only the Subaru . He is a solid worker, focused on the essentials. When it comes to traction out of the bends, the Outback makes up the ground that it loses when turning understeer under latent ESP patronage.
Opel Insignia OPC is designed to be predictable and manageable
Now something for the heart again. The Opel Insignia OPC, for example, which snorts at the start with promising key data and has great traction milling around the pylons. But with the smooth and indifferent steering, the line is difficult to feel. He resists every bend, tastes the whole width of the route. In the end, the ice crystals condense into a thick layer. On the side windows, mind you, because the Opel Insignia OPC surrenders itself wildly to the centrifugal force, scraping wildly and fleeing across both axes. The Opel system is designed to be predictable and manageable, but the fun falls by the wayside.
Let's go with the Godzilla: V6 biturbo, transaxle with dual clutch transmission and two counter-rotating drive shafts. In between, a multi-disc clutch and torque vectoring on the rear axle for selective power distribution. GT-R, let it fly.
He lets it fly - the stern. With every vicious hiss in the front, it twitches behind. A huge snow drag makes the great white man disappear into the white thicket. Only the muzzle flash of the sound waves raging through the valley is used for vague localization. First time best. But handling is no easy exercise without electronic helpers.
Audi S4 upholds the honor
Grounding again means driving a Mercedes. Down to Earth with the Mercedes E-Class , which reduces the driving euphoria to a minimum. The 4-matic rolls through the course with as little emotion as with a touring coach. The lamella lock does its best to generate clearly defined, slightly understeering driving conditions. With the Mercedes E-Class, the course can be completed safely, easily and unspectacularly. Despite all the apparent slowness, it surprises with fifth place in the handling discipline - thanks to the rock-solid handling. Three are still waiting at the start, including the Audi S4 as an advocate of the traditional Quattro philosophy. And he holds up the honor. Sure-footed, he takes a run-up, steers precisely, initially remains oversteering under load, pulls himself straight, calls for a redirect, claws at the next corner. The self-steering behavior cannot be seen as crystal clear, but the Audi S4 still moves manageable and quickly. Significantly faster than the field that has been tackled so far, but the Mitsubishi Lancer Evolution is still to come. With the smallest turbo engine in the ranks of the big and strong, it panting for air in the air, reacts heavily to load changes and accelerator pedal games, wagging playfully from left to right. Once the appropriate yaw angle is locked, there is only one thing left to do: accelerate, even if the engine control system sometimes disregards the command.
Perhaps it is this annoyance or the tires with V-identification (up to 240 km /H). In any case, there are faster ones. The Porsche 911 Turbo is not one of them. He struggles for traction, shoots the icicles off his apron with wild turbo hissing and plenty of wheelspin.
In the ranking for the largest and longest drift angle, the 11er is way ahead, but in terms of time it is way behind. It actually caught him in the frosty, high alpine environment. Is he boiling with anger now? In any case, the driver is hot from all the counter-steering.
As the only diesel in the field, the E-Class is not the fastest, but the most trustworthy. In terms of directional stability and controllability, the Mercedes is right at the top. The all-wheel drive technology responsible for this is comparatively manageable compared to some other electro-hydraulically controlled systems.
The Mercedes E-Class offers a lot of safety and little driving fun
The central differential works in concert with a two-disc multi-disc lock that is permanently pre-tensioned by a disc spring. The basic distribution of the drive torque is thus set at a ratio of 45 to 55 percent between the front and rear axles. If there are speed differences, more torque is sent to the slower rotating axis. In practice, the Mercedes E-Class presents itself with clearly defined driving behavior that tends to understeer. If the driver still drives too colorful, the ESP is always active and operates sensitively even when the control threshold is raised at the push of a button, which means that safe sovereignty is still maintained.
CONCLUSION: The Mercedes In the acceleration tests, the E-Class 4-matic pulls like an S-Bahn, builds up excellent traction and is also convincing when it comes to deceleration. A lot of driving safety, less driving fun, but ultimately second place.
In the BMW internal comparison it is striking that performance when starting up on a hill is not everything: the 258 hp BMW X1 28i is only gossamer behind the X6 M with a powerful 555 hp. Conceptually, the little one shares the concept with the big one.
Via a transfer case with a widely networked, electronically controlled multi-plate clutch, the x-Drive all-wheel drive system apportions the engine power to the axles at lightning speed. The basic distribution is 40 to 60 percent in favor of the rear axle, which benefits agility. Because the light-footed BMW X1 stays calm even in extreme situations without frantically wedging the rear end.
CONCLUSION: The X1 is pleasantly agile to drive, with very good traction and neutral self-steering behavior . When braking, it leaves springs, which also affects the handling time and is probably due to the tires. Nevertheless, place four remains.
Because the Evolution generally tends to oversteer under load and shows jagged self-steering behavior.
You can tell the rally genes of the Lancer Evolution
It is the only one that has a Torsen differential on the front axle (maximum locking effect 32 percent) disposes. The power is distributed between the front and rear axles via a multi-plate clutch. With the so-called Actice Yaw Control, the active rear axle differential, Mitsubishi was once a pioneer in the all-wheel drive scene. The way it works, the technology resembles the Audi principle and is one of the main components of the light-footed agility of the Japanese.
CONCLUSION: The Mitsubishi Lancer Evolution was designed as a rally basis from the first Note the handling meter. However, the nimble agility also needs to be mastered. Ultimately, the moderate braking values put him back in third place.
The massive (20 inch) and wide rear axle tires have a counterproductive effect on the snow-covered roadDirectional stability. In terms of the quality of its elaborate all-wheel drive system, the GT-R plays in the top league.
The Nissan GT-R requires a lot of sensitivity
A multi-plate clutch directs up to 50 percent of the power to the front axle. Due to the transaxle construction, this is done by a second, opposing cardan shaft. The high-tech package also contains a so-called Electronic Torque Split - a rear axle differential that, similar to the Audi S4, uses lamellar technology to variably distribute the powerful forces of the Nissan GT-R on the rear axle.
CONCLUSION: The Nissan GT-R requires a lot of sensitivity in order to pour the brute performance into a good lap time. With driving aids, however, the GT-R is relatively uncritical to move. In the competitive environment, it ranks in the bottom third.
Even if the electromagnetically controlled multi-plate clutch is supposed to shovel the force of the hissing boxer forward within 100 milliseconds - little of it is subjectively noticeable on snow.
The Porsche 911 Turbo brakes best
While the Turbo 911 remains extremely neutral on dry asphalt, it drives like an honest one with very low friction values Rear-wheel drive: oversteer, is steered with the gas pedal. The stern does not jerk out suddenly, but gently announces itself. Thanks to the rear axle lock, at least the drift remains controllable. The additional torque vectoring works by means of braking intervention, whereby more drive torque is transferred to the opposite side.
CONCLUSION: At least in one instance, the 911 stays true to its line even on snow - it brakes preferably. In terms of stability and controllability, however, it cannot convince. The stability control gets a lot to do.
The mixture of driving safety and agility helps the Quattro achieve the best time. Technically, the Audi S4 follows the rules that have been in force in Ingolstadt since 2005 for models with a longitudinal engine. This means that the Torsen center differential basically distributes the power of the supercharged V6 engine between the front and rear axles at a ratio of 40 to 60 percent in favor of increased dynamics.
The Audi S4 creates the most balanced performance
The mechanically operating Quattro system is supported by a so-called sport differential on the rear axle. Electrohydraulically controlled multi-plate clutches vary the torque flow between the two rear wheels. To counteract understeer, more engine torque is supplied to the wheel on the inside of the curve, for example. In long curves, the Audi S4 requires a slight amount of steering, which is easy thanks to the direct steering. Long drifts are not the primary goal of the Audi S4, it straightens as quickly as possible, which is what the Quattro doesmakes it the fastest in handling.
CONCLUSION: All in all, the Audi S4 has the most balanced performance. Even if it does not act at the very front when braking or in terms of directional stability - with 93 total points it emerges as the winner in the all-wheel drive comparison.
Basically, the Insignia drives as a front-wheel drive, but lets the cardan shaft rotate at all times.
The Opel Insiginia OPC lacks the sporty orientation
An electrohydraulically controlled multi-plate clutch on the rear axle then distributes the engine torque to the rear as required, and also between the rear wheels themselves, the power can be varied depending on the situation. In terms of longitudinal dynamics, the Insignia OPC mixes with the best, and the lag is also good. However, it turns in sluggishly and pushes over all fours.
CONCLUSION: Although the technical key data of the Insignia OPC are promising, even when accelerating without ESP, the rear pushes itself out of the lane with emphasis . Unfortunately, there is no sporty orientation in handling. With 76 points, the OPC is in the middle of the field.
The BMW X6 scores with very good traction
If the load comes into sliding friction, it glides far. However, the activated ESP does not even allow it to get that far, but regulates it early and cleanly, doses the power to a suitable level and thus defuses the handling of the mighty BMW X6 on snow. The hardware of the all-wheel drive is based on an electronically controlled multi-plate clutch that regulates the situation-related power flow between the front and rear. With a basic distribution of 40 to 60 percent, the X6 is also designed to be typical of x-Drive. In addition, the 555 PS strong Bavarian has what is known as Dynamic Performance Control on the rear axle.
A double planetary gearbox is flanked by two electrically controlled multi-plate clutches, which ensures an increase in torque between the right and left rear wheel. In practice this means: If the X6 tends to oversteer, more power is allocated to the wheel on the inside of the curve. And in extreme cases, the X6 actually pushes gently over all fours off and not suddenly with the rear.
CONCLUSION: As far as propulsion is concerned, one can only salute the very good traction of the X6 M. Without ESP, however, the 2.4 tonnes are latently off track. The deceleration of the mass is also not optimal. In the end: fifth place.
The basic distribution of power is also at the same level, 45 percent in the front to 55 percent in the back.
The Subaru Outback does its job reliably
When the clutch is fully locked, the engine torque is distributed as required. In practice, the Subaru presents itself as a sluggish understeer. He shows neither great strengths nor glaring weaknesses.The ESP, which is always present, reduces driving fun to an absolute minimum.
CONCLUSION: A solid climber who is not to blame. Traction, handling and deceleration are at a good level. The outback does its job reliably and unemotionally. In the final statement, he remains in the lower midfield.
When accelerating, braking and handling, the off-road vehicle is left behind. Subjectively, the safe, understeering driving behavior of the GLK that of the E-Class.
The Mercedes GLK is safe and solid
No wonder with an identical basic distribution (45 to 55 percent) using a center differential and multi-plate lock. At most, the shorter wheelbase of the GLK reduces the directional stability somewhat compared to the Mercedes E-Class.
CONCLUSION: The GLK works safely and solidly. He tends to understeer, which limits driving pleasure. The ESP also regulates in switched-off mode, but then late and not over-engaged. The moderate delay costs points - ninth place.
