What’s in an all-wheel drive system?
Although more and more consumers in Canada are insisting upon the inclusion of all-wheel drive when purchasing their crossover sport utility vehicles, not all implementations are created equal. While just about any form of AWD from any automaker will get you through your typical winter snowstorm, there’s much more variability when it comes to how much control you have to go with the additional traction AWD brings. In other words, all AWD systems will greatly improve traction to get going without getting stuck, but very few make as significant inroads when it comes to control. The more advanced setups offer extra improvements to cornering and driving dynamics that are often overlooked.
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This week at Daddy’s Digest, we examine the 2022 Acura RDX Platinum Elite A-Spec, which comes with the Japanese luxury marque’s Super Handling-All Wheel Drive (SH-AWD). As the name implies, the fancy compact crossover from parent company Honda gets one of the best all-wheel drive systems in the business thanks to its torque-vectoring approach. To get a better understanding of SH-AWD, let’s start with some of the less advanced drive systems found on today’s crossover SUVs.
Slip and Grip – also known as a Limited Slip Centre Differential, these systems are often at the bottom of the all-wheel drive hierarchy. They’re the least complex, which can be good in terms of cost of entry and may be easier on the wallet in terms of long-term maintenance and repair costs. In normal driving conditions, these systems are mostly or entirely two-wheel drive, sending engine power to either the front or rear wheels. When wheelspin or a loss of traction occurs between the front and rear wheels, the AWD system passively reacts and starts to send power to the opposite end of the car through the mechanical coupling in the centre differential. Examples of cars equipped with “slip and grip” include the RDX’s mainstream cousin, the Honda CR-V, and the manual-transmission equipped Subaru WRX.
In practice, the “slip and grip” systems can get you out of most situations encountered by the average driver. In terms of added steering and handling control, however, they may not be as good for driving dynamics as most people think. Because of an inability to control the left and right side power distribution at each axle, engine torque will take the path of least resistance, and a lack of traction on one side of the car means that these all-wheel drive systems can quickly become one-wheel drive when one wheel has zero traction or is in the air. In other words, you still might get stuck if one wheel is confined to slipping hopelessly. These systems are most ideal in one dimension only – when under throttle.
AWD with Front and/or Rear Limited Slip Differentials – additional limited-slip differentials at the front and/or rear axles can solve the problem of the left/right power distribution conundrum under low traction scenarios. When power is sent to the front or rear axle, the limited-slip diff(s) ensures a much more even torque split. When the going gets tough, having a more even torque split between left and right helps to pull cars through corners, which delivers more sure-footed performance when adding steering and throttle input into the mix. Examples of such systems include the Subaru WRX STI (both front and rear), and the 2022 Kia Stinger (rear only).
Torque Vectoring All-Wheel Drive – This is where SH-AWD comes in. Where a conventional mechanical limited-slip differential at the front and/or rear axles can lock power somewhere close to 50/50 between left/right, a torque vectoring all-wheel drive system uses additional electromechanical controls to finely tune the amount of power that each wheel gets. In the case of the 2022 RDX, up to 70 percent of engine power can be directed to the rear wheels, and on top of that, the entirety of that 70 percent can be directed to an individual rear wheel. This translates into even more agility and fine control compared to any other AWD system. Use of the throttle is much more effective when it comes to rotating the car into and out of a corner, and the rotation and steering input happen with a ton of extra precision. Other than the RDX (and various other Acura products such as the MDX, TLX, and the NSX in a hybrid variant), torque vectoring AWD was used on a couple of now-discontinued cult classics – the Ford Focus RS and the Mitsubishi Lancer Evo.
In reality, there were plenty of opportunities to put the RDX’s SH-AWD system through its paces. Firstly, the Acura was picked up during a snowfall event. Shod with some higher-end Michelin Latitude Alpin LA2 winter tires, the RDX was practically unstoppable and inspired the utmost of confidence behind the wheel. Of course, drivers still need to remember to drive according to conditions and go only as fast as they can safely steer and stop, but under almost any circumstances, there is zero need to worry about whether the SH-AWD system knows what it’s doing. It’s as sure-footed as any crossover SUV can get!
As for the rest of the RDX, prices range from $45,800 for the base model to the $58,000 as-tested for the Platinum Elite A-Spec. All trims get a 2.0-litre turbocharged four-cylinder engine that pumps out 272 horsepower and 280 pound-feet of torque, and power is routed through a ten-speed automatic transmission. The powertrain is very smooth and offers a ton of grunt at low revs, while still being playful in a manner similar to what you’d find in a Volkswagen GTI. Steering and brake feel are strong points, and when pairing all this to the SH-AWD system, it’s one of the best-performing cars in its class, including when put up against the BMW X3 xDrive30i or Mercedes-Benz GLC 300 4MATIC.
The interior of the Acura RDX is well-designed and is a comfortable place to spend time in, with easy-access LATCH/ISOFIX anchors for child seats, and enough cargo space for families of four. Downsides are few and far between, and are mostly limited to the infotainment system – it utilizes a laptop-style touchpad without any touch screens. While functions like volume and climate control are adjusted using hard buttons and knobs, the infotainment is restricted to the touch-screen only. It’s impossible to use while driving without creating major driver distraction, and when stopped, it’s still less than ideal. Android Auto and Apple CarPlay smartphone pairing interfaces also aren’t necessarily optimized for a touchpad, so expect the learning curve to be steep – be sure to try before you buy.
Overall, the 2022 Acura RDX Platinum Elite A-Spec is one of the best-performing luxury compact crossovers for the money. The slick Super Handling-All Wheel Drive system makes the road beneath you anything but, a well-calibrated powertrain is an eager and willing dance partner, and a high-quality interior (other than the cumbersome infotainment) looks and feels the part. The Acura does all of this while undercutting its European rivals on cost, and deserves a good look from anybody shopping in this category.
