Let's face it, the current automotive climate breeds lazy drivers (see automatic cruise control, lane-keeping assist, and the decreasing availability of manual transmissions). So it seems incumbent on us to celebrate genuine advancements that improve a driver's ability to actually control a car with one's own appendages, whether while going fast on a racetrack or just taking the family to the beach. There's an interesting new one over at Mazda, where the driving forecast is sunny.
-The brand from Hiroshima ranks remarkably high on the overall fun-to-drive scale, especially considering its size and resources. The Mazda 3 and the MX-5 Miata reside on the current 10Best Cars list and the Mazda 6 is a previous winner. The company's SUVs drive like cars, and its interiors deliver visual punch a weight-class above their prices. In short, Mazda cares about making cars that people actually find enjoyable to drive themselves, which is why we flew to Mazda Raceway Laguna Seca, outside of Monterey, California, to go around the track at a mere 30 mph. Mazda wouldn't even tell us what G-Vectoring Control (GVC), the technology it planned to showcase, actually was before letting us sample it in the 2017-spec Mazda 6.
-The day started with laps of an impromptu oval in the parking lot at a blistering 20 mph. An engineer would switch the Mazda 6s between GVC active and GVC off from the passenger seat. At first, GVC just feels as if it makes the steering a little heftier. But after a few of these cruise-controlled laps while hugging a line of pylons, we realized that turn-in is smoother and rarely did we have to correct our driving line. Watch this video to see the difference, paying attention to the white line on the steering wheel:
-But we were still in the dark about what GVC actually does. Given the name, you might expect it to be some kind of torque vectoring, or steering the car by controlling differential torque delivery between the inside and outside wheels in a corner, which is analogous to how tanks turn. But that's not what GVC is doing. Mazda finally explained that the important part of GVC is the G, or as you see it frequently, g. By closely monitoring the speed of the driver's steering-wheel inputs, GVC tells the engine to ever-so-slightly reduce torque. This produces an imperceptible deceleration, only 0.05 g in the most extreme cases. (By way of comparison, lifting off the throttle in a typical car results in about 0.20-g deceleration.) The tiny change generates a small shift in load to the front axle, which tightens everything in the front suspension and steering system, removing compliance in bushings and dampers and resulting in improved steering response. It is remarkable how such a tiny influence can contribute such a dramatic change. Engineers hesitate to quote a lb-ft figure but they did confirm that GVC reduces engine torque by a single-digit percentage, usually by retarding the timing. At a steady 20 or 30 mph, the 6's 2.5-liter might be putting out 20 lb-ft, so even 9 percent would be less than 2 lb-ft reduction.
-The whole project was eight years in the making and it developed out of an extensive study of how humans move and how, when controlling cars, drivers make similar movements and react to g forces. After proving the concept with an EV—used because electric motors allow ultra-fine control of incremental torque delivery—Mazda had to wait for its range of Skyactive engines to reach the mainstream before developing the technology for production cars. Mazda's newest engines have granular and rapidly responsive control over torque output. Creating the slight deceleration is one thing, but getting it to happen in a small amount of time—0.05 seconds—so that the driver and passengers wouldn't notice, is the real key to making GVC appear seamless to occupants.
-Essentially, GVC mimics techniques, like "breathing" the throttle or left-foot braking into a corner, that race and rally drivers use to generate more front-wheel grip and get their competition cars to turn, only it's extremely subtle, never felt or obvious. While going fast is always a hoot, GVC is more of a comfort- and confidence-builder than anything else. It will not improve skidpad grip or shave seconds off of any driver's fastest lap time.
-After explaining what GVC does, Mazda had us lap Mazda Raceway at 30 mph, hugging the inside edge of one corner to stay on the same line while an engineer in the passenger seat switched the GVC system on and off, as we'd been doing before on the parking lot oval. From the driver's seat, there are fewer corrections needed, particularly when making quick changes in direction, when a driver might otherwise crank in too much steering angle. With GVC at work, you're less likely to over-shoot your steering input because there's less delay caused by the previously mentioned compliance that's baked into the front suspension and steering. That compliance is there to improve ride quality and reduce noise (racers often replace the bushings and mounts with stiffer elements to improve responsiveness, trading away comfort in the process). From the passenger seat of a Mazda 6 with GVC, we clearly could see other drivers making fewer small steering corrections. This limits head toss and torso movements significantly for all occupants. Fewer corrections also reduce driver fatigue, again, improving comfort.
-Mazda also simulated a narrow-lane construction zone using tall cones and Jersey barriers on Mazda Raceway's front straight. Many drivers never notice it, but going dead straight requires that they make a lot of little steering corrections. With GVC turned on, these corrections become less extreme and fewer in number, again reducing driver fatigue.
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The really difficult part for Mazda is conveying this information to the car-buying public. The finer points of how GVC works will be lost on most customers, which is not really a problem in itself. All they need to understand is that GVC improves an already class-leading steering system, making for a better-driving car. GVC comes standard on both the 2017 Mazda 3 and 6, and we expect to see it proliferate across the rest of the Mazda lineup within a few years. The Mazda MX-5 Miata is one model that may never get GVC because its suspension has less compliance and a lot of anti-lift baked into its geometry. But we have no doubt that Mazda will find other ways to make that car even more fun to drive in the coming years.
-from Car and Driver Blog http://ift.tt/nSHy27
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