MONTREAL—In winter, vehicle-stability technology lets you drive faster and with a greater sense of security, right up until the moment you plant the car into a big, fluffy snowbank. Twice. Ask me how I know. And how I managed to do it with a winner of the 24 Hours of LeMans in the right-hand seat explaining how to do it right.

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To help you cope with snow, slush, mud, loose gravel, and slippery boat launch ramps, vehicles have progressed from two-wheel drive through four-wheel drive (and the similar all-wheel-drive), and front drive. Many have a limited slip differential or locking differential to redirect power away a wheel on a slippery surface.

In addition: Traction control modulates the throttle to improve your car's grip on every kind of surface. Stability control helps your car stay poised when cornering, in crosswinds, and on slippery surfaces. While stability control has a lot of names, including automatic stability control (ASC), electronic stability program (ESP), vehicle dynamics control (VSC), vehicle stability assist (VSA), StabiliTrak (GM vehicles), and Advance Trac (Ford) it may be the single most important safety factor on top-heavy SUVs.

Now comes a newer technology, torque vectoring, that provides more power to each of the wheels as needed. Think of it as additional road-wheel power minus the electrical drain (minor) used up by the microprocessor power (major) needed to figure out which wheel gets what. Acura was first with the technology in 2005 in the RL sedan and hid it under the most awkward of names, Super Handling-All Wheel Drive, typically pronounced S-H-A-W-D (never as shawd), which still takes seven syllables to speak, more than a lot of law firms have in their names. Now with reports that Audi's Quattro all-wheel-drive system will add torque vectoring, SH-AWD merits a closer look.

I got hands-on experience with torque vectoring outside Montreal at Circuit Mecaglisse, a racetrack used especially for rally-driver training. Starting in December, the tracks and skidpads are watered down and quickly freeze, and with snow on top, you have a devilishly slippery training ground.

Acura brought its three SH-AWD cars—the RL sedan, medium-small RDX SUV, and medium-large MDX SUV—to Mecaglisse along with all-wheel-drive competitors from Audi, BMW, Lexus, and Mercedes-Benz for comparison driving by a group of two dozen journalists. All the cars and SUVs had front/rear and left/right limited slip functionality, engine power modulation under acceleration, individual braking rates for the four wheels, and (except Mercedes) the ability to vary the ratio of power going to the front versus the rear wheels. Acura's point in all this was to show how torque vectoring might provide an extra margin of performance and safety.

To explain the finer points of driving style, Acura called on the circuit's resident instructors and brought in respected racers such as Davy Jones, who won LeMans and finished second in the Indianapolis 500, both in 1996.

Here's what I learned. First, all the cars are quite good in snow. All-wheel drive and traction control helps cars go in winter conditions. So do snow tires on all four wheels, as I wrote about recently (Testing Snow Tires Where It's Always Icy). Stability control helps you when road conditions are worse than anticipated or when drivers get in over their heads, and it can help keep an SUV from flipping. (I couldn't see buying a used SUV without stability control, no matter how low the price.)

Beyond that, torque vectoring as used by Acura did provide an extra margin of driving performance. In back-to-back driving between the Acura RDX and BMW X3 on a short road-racing course with elevation changes, the RDX was able to reach the apex (the inside point of a turn), drift out (slide off a bit), and then regain some semblance of control sooner and start turning in to the next corner sooner than the X3. And BMW's X-Drive is probably the most sophisticated all-wheel-drive system outside SH-AWD, even up to the point of providing a form of active torque distribution, but by braking an individual wheel opposite the wheel that needs more power, rather than by Acura's directly applied power to the wheel that needs power.

When a car goes around a corner, the weight shifts to the outside tires and the body rolls away from the turns. Turn right and the body leans left; more weight is on the left-side tires. That's the law (of physics). With SH-AWD, Acura directs (a simpler word for vectors) more power (torque) to the car's outside wheels and, typically, more power to the outside rear wheel. It helps power you through the turn.

To make this happen, Acura embeds electronically controlled clutches in the rear axle, one for each wheel. In extreme cases, 100 percent of the power going to the rear of the car goes to the outside wheel. Front/rear power is also variable, up to 70 percent rear for acceleration or hill-climbing. At higher speeds on slippery roads, power is biased toward the front wheels for a more stable feel.

Acura's torque-vectoring SH-AWD works with stability control in turns to control understeer or push (when a car doesn't want to turn as much as you want), as well as oversteer (when the car wants to turn more than you want, up to the point where the rear of the car breaks loose). SH-AWD creates a yaw moment, which is airplane speak for when the vehicle is left or right of its intended path when you're looking down from above. On all these cars, several electronic control units (ECUs) work together. In the case of Acura, that includes engine/transmission ECU, stability control ECU, SH-AWD ECU, lateral g sensor, front/rear g sensor, steering angle sensor, yaw rate sensor, and wheel speed sensor.

All these technologies provide a bit more traction, cornering, and confidence. But there's a limit to how much you can tinker with physics. On the longest of the road courses, the Audi Quattro Q7 was pitted against the MDX. Audi does well on traction and hill climbing with its three-differential solution.

The MDX was great going from a standstill to a power-on left turn onto the course (imagine a left turn in snow against oncoming traffic), and was precise and maneuverable at country-road speeds. But then, coming off a turn and heading for a series of lane-change pylons, I carried too much speed for the combination of SH-AWD, stability control, and steering inputs. The MDX understeered into a waist-high snowbank, sending a shower of fluffy white powder everywhere. It took a backhoe (with tire chains) to pull us out.

In addition, on an uphill-downhill skidpad (most are flat and level) for the sedans, one of the exercises was to drive with the gas pedal all the way to the floor, to see how the various electronic assists come into play. At lower speeds, all the cars were pretty good; I thought the Acura RL had a slight advantage over the Mercedes-Benz E350 4-Matic and Lexus GS350 AWD, but the big difference was how much better all were than front-drive-only or rear-drive-only cars.

On the pedal-to-the-metal exercise, with the car going sideways but the steering wheel straight ahead, the Lexus engine roared to life again and the car proceeded to slide backwards into a firmer snowbank (on that, I was far from alone), leaving a nice license plate imprint, before we drove off under power. The Lexus also has a warning beep that goes off (and keeps on going) once you've lost control, at which point it's a scold, not a driving aid.

Building on what I learned driving snow-tire cars on hockey rinks, all-wheel-drive and SH-AWD drive cars on race tracks in summer (The Best Luxury SUV You Can Buy Today), and now AWD and SH-AWD cars on snow-and-ice-covered racetracks, it's clear that technology makes for safer driving. The greatest gains are from snow tires in snowy months and from technologies available on the majority of cars (stability control and traction control). The benefits of these technologies are year-round. Super Handling All-Wheel Drive is a step forward.

The most important lesson is that the very best technologies can't overcome a driver bent on exploring and exceeding the limits. I was lucky to learn on a no-harm, no-foul race course ringed with snow. Too bad this kind of learning experience isn't available to everyone, especially teenagers just starting out.