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Buick's new Active Twin Clutch all-wheel-drive system is the latest application of torque vectoring to make cars perform better in the worst and all-time driving weather. This means it improves handling and stability on snowy, icy roads, also every bit on dry out surfaces. Testing on a snow-covered racetrack skidpad showed Buick'due south twin-clutch arrangement got around the class with more poise than a decade-onetime design used by Acura.

The Active Twin Clutch organisation is on the Buick Envision, a just-shipped compact "world course luxury crossover" (Buick's words) and the refreshed 2022 Buick LaCrosse, a midsize sedan.

Buick Envision AWD uses 2 electronically controlled clutches, no rear differential. Power can exist directed front-dorsum, left-correct.

What is torque vectoring and Buick'due south twin clutch organisation?

Torque vectoring is a engineering dating dorsum 2 decades. It delivers power (torque) to the wheels that demand information technology most. Going effectually a corner, the outside wheel may encompass, say, 5% more altitude. To aid ability the automobile through the turn, a torque vectoring system might deliver 7% more torque to overdrive the bike and force the car through the turn. In snow-ice conditions where the auto may be near the limits of control, more complex calculations determine the driver'southward intended path.

On some cars, it's an electronics-only system that brakes the inside wheel slightly and so the outside wheel is overdriven in comparison. This can be used on front end-bulldoze-simply cars. Merely more torque vectoring systems are on all-bike-drive systems, a combination of electronic and mechanical systems, such as Audi's Quattro system, Acura's Super-Handling All-Wheel-Drive, or BMW's Dynamic Operation Control.

A typical all-cycle-bulldoze motorcar uses a clutch at the front end axle that controls how much torque goes to the rear wheels. So the rear differential splits the torque between left and right rear wheels.

The Buick Active Twin Clutch system comes from British supplier GKN Driveline. Information technology uses a pair of electronically controlled clutch packs in the rear driveline module. They tin send up to 100% of the power to the front end, or dorsum, or carve up the power as needed. They also split the torque between the rear wheels and ship as much as 100% of the the power to the left or correct rear. Up front end, the system makes certain each wheel receives some ability.

GKN systems similar to Buick's are on the Cadillac XT5 midsize crossover, Land Rover Evoq, and Ford Focus RS. The XT5 also tin can disconnect the motorcar from the AWD arrangement at speeds over 40 mph in Touring manner to save fuel.

Torque vectoring also improves treatment on dry roads. Part of Buick's focus on the twin-clutch engineering is to boost sales of AWD cars outside the snow chugalug.

The comparison exam

Buick took over the Lime Stone Park racetrack in northwestern Connecticut and brought in snowmaking machinery to bring even more wintertime to the Berkshires region. A low-speed (fifteen-thirty mph) handling grade was set up with an emergency lane change, slalom, and sweeping corners. The compact Buick Envision was matched against the bestseller in the Acura lineup, the midsize Acura MDX with Super-Handling All-Wheel-Drive. The meaty Acura RDX would be a closer size match, but the second-generation (2013-present) RDX no longer offers SH-AWD.

Both cars ran on all-season, not winter, tires. The Envision specifically had Hankook Ventus S1 Noble 2 235/50-xix inch tires. Both cars had good grip when accelerating. Going through the slalom, getting on and off throttle, then braking, the Buick felt more poised. Going around a sweeping turn, both did well, although the Envision carved a tighter arc. It wasn't and then much skillful-versus-bad as improve-versus-skillful. In both cars I managed to get off grade (into more snowfall) several times, because too much throttle tin can be a bad affair on snow.

Acura MDX, roller test

Often an automaker running comparison tests sandbags the competition with a test the other guy can't handle. Mazda did it to Subaru a year ago in a snowy-hill-climb-and-right-plow test. In this example, it was the roller exam.

Here, the Buick and Acura were placed on rollers nether each wheel except the left front, and so three wheels had zero traction and the one traction surface was under the front not rear wheel. In this instance, the Envision could deliver torque to the left forepart cycle and drive off. The Acura could not and had to be pushed off; information technology could get going if the wheel nonetheless on the basis was a rear wheel. What does this prove? In the occasional circumstance where yous're stopped and both rear wheels and one forepart cycle are on, say, glare water ice, only one car, Buick, volition be able to start up without a button.

Buick Encore subcompact crossover.

More than winter driving tests

Buick ran a pair of additional tests to show the superiority of its vehicles. Let'southward call them the "well, what did y'all look?" tests.

I was the Boston post-snowstorm parking examination. Crowded Boston has more cars than parking spots. In winter, a resident may dig out a space for his or her auto, and so protect the space with pylons or lawn chairs so some other driver doesn't profit from his neighbor'southward labor. The challenge was to parallel park into a tiny infinite, ane so small the neighbor'due south larger cars might non fit. The combatants were the subcompact Buick Encore subcompact crossover, 168 inches long, and the Toyota RAV4, 184 inches long. Not surprisingly, it was easier to park the Buick, though not everyone was successful. And when the test was finished, the Encore had an iPad-sized paring in the rear tailgate when it rammed an overhanging chunk of icy snow.

Conclusions: a) shorter cars are easier to parallel park and b) automatic parallel parking using the car'due south parking sonar would be better than nearly drivers.

The second test was a hill climb — actually a fairly gentle upwardly gradient of snow with a bit of ice. The exam pitted a midsize Buick LaCrosse with all-cycle-drive and all-flavor tires against a Lexus ES 350 that comes forepart-drive simply, with all-season tires. With very little wheelspin (Buick) and a lot of wheelspin (Lexus), both cars climbed the loma.

Determination: All other things equal, all-wheel-bulldoze beats front drive in the snowfall. In case you didn't already know. An interesting test would have been to include a front-bulldoze LaCrosse with winter tires. They'd come close to matching an all-wheel-drive car with all-flavor tires, and they'd be superior on braking.

Nevertheless, this shows that Buick, known for affordable luxury and living midway between Chevrolet (mainstream cars) and Cadillac (trying to reattain The Standard of the World aura), is calculation performance and technology to its resume.