Testing Acura's Super-Handling all-wheel drive system
Testing Acura’s Super-Handling all-wheel drive system. Click image to enlarge

Article and photos by Paul Williams

Photo Gallery: Testing Acura’s Super-Handling all-wheel drive system

Notre-dame-de-la-merci, Quebec – Although all-wheel drive (AWD) has been available on consumer vehicles for several decades, it’s only in the last few years that the option has become popular across several brands and price points. In Canada, especially in the luxury segment, all-wheel drive as a percentage of vehicle sales is rising steadily, year after year.

Given the general advantages and acceptance of all-wheel drive, Acura would certainly like consumers to become as familiar with its recently introduced “Super Handling All-Wheel Drive,” (SH-AWD) system in the same way that Audi is associated with “quattro” and Mercedes-Benz with “4Matic.”

But it’s not just because of branding. Beyond the Acura AWD system’s mouthful of a name, “Super Handling All-Wheel Drive” is a noteworthy advance over competitive products.

Hailed in engineering circles as a breakthrough development in all-wheel drive systems, SH-AWD features what Acura chief engineer Shiyouji Tokushima calls “Direct Yaw Control,” also known as Torque Vectoring. In fact, the term “torque vectoring” is gaining popularity when describing this kind of technology, and other manufacturers are now looking to develop similar systems.

Testing Acura's Super-Handling all-wheel drive system
Testing Acura’s Super-Handling all-wheel drive system. Click image to enlarge

The torque vectoring characteristic that distinguishes SH-AWD — and what so impresses the competition — is that the rotational speed of one rear wheel can be increased to improve stability and handling.

Think of it this way: you’re going around a corner, and centrifugal forces are pushing the vehicle outwards, as you steer inwards to keep it online. Now imagine the SH-AWD system doing the compensating for you. Its torque vectoring properties enable the outside rear wheel to accelerate slightly in order to compensate for the forces pushing on the car as you round the bend. The result on dry pavement is a feeling that the vehicle is behaving much as it does when going straight, even though you’re rounding a corner. On snow and ice, there are also advantages.

Testing Acura's Super-Handling all-wheel drive system
Testing Acura’s Super-Handling all-wheel drive system. Click image to enlarge

The system is comparatively simple, according to Mr. Tokushima, using a transfer case at the front, and a rear differential and two clutches at the rear to distribute torque. It is “proactive,” as well, meaning that SH-AWD anticipates vehicle behaviour in particular conditions, and continuously compensates (it’s “always active” says Mr. Tokushima) by distributing torque between front and rear wheels, and from side-to-side at the rear.

Likewise, if you’re accelerating through a corner, and you abruptly take your foot off the gas, the SH-AWD system will work to stabilize the vehicle.

In case you’re wondering, this is different than electronic stability control, where the throttle and brakes are selectively applied when sensors detect wheel slip. In many cases, in fact, braking responses from some stability control systems can come on too suddenly for many drivers, almost stopping a vehicle. Often, it’s acceleration that’s required to enhance stability, and here is where SH-AWD uniquely (at this point in time) has an advantage.

Testing Acura's Super-Handling all-wheel drive system
Testing Acura’s Super-Handling all-wheel drive system. Click image to enlarge

Of course, SH-AWD doesn’t replace electronic stability control (Acura calls theirs “VSA”) and traction control. These technologies “cooperate” with SH-AWD to optimize traction and handling. On Acura vehicles, the stability control system can be driver deactivated if desired, and the SH-AWD will work independently.

To demonstrate the SH-AWD system, Acura brought journalists to the snow and ice-covered Mecaglisse driving centre near Notre-dame-de-la-merci, about 90-minutes north of Montreal. Competitive vehicles from Lexus, Audi, BMW and Mercedes-Benz were available for comparison, but the spotlight was on the Acura RDX and MDX sport utility vehicles, and the luxury RL sedan, which all come standard with “SH-AWD” (the RDX and MDX feature the latest version).

All of the competitive vehicles performed acceptably well on the purpose-designed tracks, and better than a comparable front or rear-wheel drive vehicle would (except for the Lexus GS 300, which did not flatter itself on the circular ice track). However, the Acura vehicles were distinguished by the smoothness of their operation, and their ability to maintain steering response in several situations where the competition had lost control.

Testing Acura's Super-Handling all-wheel drive system
Testing Acura’s Super-Handling all-wheel drive system. Click image to enlarge

It was noted that the all-wheel drive and stability systems on the competitive vehicles tended to intervene more abruptly and severely than the Acura vehicles. In comparison, the operation of the SH-AWD system and VSA was barely perceptible (a good thing!), and enabled corners to be taken on very slick surfaces without drama. Furthermore, some of those corners could be taken comfortably at twice the speed of the competition, although driving experience was a factor in achieving this level of performance.

Don’t get the idea that SH-AWD will enable you to maintain control in any situation. It won’t, and neither will any other traction technology. If you’re going too fast into a corner, for instance, your momentum will trump any stability system.

But in everyday driving, on wet, dry and icy conditions, the torque vectoring properties of Acura’s SH-AWD have discernable advantages in handling and performance.


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