An ingenious new Mazda technology called G-Vectoring Control emulates race-car driver weight-transfer techniques to make road-going cars driven by mere mortals handle better and make passengers feel more comfortable. Every time the driver turns the steering wheel, GVC shifts a tiny amount of weight to the outside front tire, which improves grip and steering response. The result is less sawing at the steering wheel to find the right path through a turn, or less effort to keep the car pointed straight on the highway. G-Vectoring Control is not just another over-hyped modest performance tweak. Mazda appears to have developed a significant electronic driver enhancer.
The driver and passengers will subconsciously believe the car handles better (it actually does) and the driver is a better driver (possibly). It is a significant step forward for Mazda in making mid-price cars and crossovers carve corners like high-end German sport sedans and maintain arrow-straight stability on long, straight highways. Mazda G-Vectoring Control debuts on 2017 Mazda 6 and Mazda 3, with the rest of the line to follow over the next couple years.
When a car slows or brakes, the weight shifts forward. That’s physics. The weight transfer puts weight on the front wheels, so they grip better and turn in a little more. Race drivers are taught to brake just a little heading into a turn to initiate the weight transfer. Mazda GVC automates the process. As soon as the driver turns the wheel, Mazda’s SkyActiv engine management system — which includes the GVC algorithms as part of what Mazda calls SkyActiv Vehicle Dynamics — retards the ignition timing ever so slightly, engine torque (power) falls slightly, the car slows ever so slightly, and a small amount of weight transfers to the outside front wheel (such as the right front wheel if the steering wheel is turned to the left, as in the illustration above).
All this takes place in less than 50 milliseconds (one-twentieth of a second) from steering wheel input to torque reduction, so it’s effectively instantaneous. A Formula 1 race driver couldn’t do all that in 50 ms. The change in speed is so slight, 0.01G to 0.05G, Mazda says, that “deceleration is not consciously detectable by the driver.” The amount of weight transfer is at most 10 pounds, but it’s enough. Mazda found that using the brakes to slow the outer front wheel took too long and was imprecise (too much or too little braking), as did slowing the engine in other ways, such as reducing fuel flow.
Mazda set up a series of demonstrations in Monterey, CA, at the Mazda Laguna Seca Raceway using a set of instrumented Mazda 6 sedans outfitted with an on/off button for GVC, and a laptop-equipped backseat technician that videotaped and recorded steering wheel input for back-to-back laps with GVC off, and then on.
The A-B testing included a emergency lane change slalom, an oval, a water-soaked high speed turn, and a narrow lane set off by cones on one side and the famous racetrack’s unforgiving concrete wall protecting pit road.
The video above shows a 30-second oval driven at the same moderate speed with G-Vectoring Control on and off. Notice the more frequent micro-corrections of the wheel with GVC off. With GVC disabled, the driver is likely to turn in too much or too little, over-correct, correct for the over-correction, and so forth. Those more frequent sawing motions at the wheel are on the right video. The line chart shows the greater smoothness with GVC enabled (blue line), especially the first half of the lap. (Where the blue line diverges in the middle, I swung wide to set up for the second turn, a no-no; drivers were supposed to hug the inside of the course all the way around, each lap.)
On the oval the most notable difference was how little steering input (corrections) I had to make going around the turns. On the long narrow lane on the track’s main straight, the difference was how stable and centered the car seemed, almost as if the lane was a couple feet wider. On the highway, that should translate to a car that seems to go where you want it to (straight ahead) with fewer corrections.
Mazda has been working on GVC for eight years, much of it in conjunction with Hitachi, according to Mazda vehicle development engineer Dave Coleman. That included deep-dive research into how drivers and passengers react to the forces of motion. One topic of study was equilibrioception, or how people maintain (and lose) their sense of balance. People like to keep their heads straight upright, and doing that serves as the body’s internal G-sensor. (See the YouTube video Chicken Head Tracking below for proof that other parts of the animal kingdom want to keep their heads straight up, too.)
The minimum jerk theory was also studied and, no, it has nothing to do with who’s likely to win Election 2016. Basically, human motion includes jerky motion that we try to smooth out as much as possible. Driver and passenger are upset by jerky motion, which Mazda says is not velocity (going a steady 60 mph even though the roadside looking out may be a blur), nor is it the delta (change in) velocity, which is described as acceleration. Rather, “jerk” is the change in acceleration, and it shows itself as repeated steering wheel adjustments, or pressing softer then harder on the brakes, or pressing more then less on the throttle. With a turbocharged car, when you tromp the throttle, the car moves off and the jerk moment comes a fraction of a second later when the turbo boost finally takes effect. Jerk motion is unsettling.
Turning into a corner involves at least a small jerk, and each time the driver corrects again, there’s another jerk. With GVC, there are fewer mid-turn corrections.
Mazda says G-Vectoring is not the same as torque vectoring. Torque vectoring is a mechanical or brake-induced action to over-drive the outer powered wheel going around a corner, effectively powering the car through the turn. Mechanical torque vectoring can add 100 pounds or more or weight to the car. Brake-controlled torque vectoring brakes the inside wheel, effectively overpowering the outer wheel in comparison. According to Mazda (chart above), G-Vectoring Control has the advantage of working in more situations than torque vectoring, most of all in everyday conditions where it makes the car seem more stable and on-course.
Mazda is an engineering-driven company that sees itself the equal of Toyota or Honda, albeit with one-fifth the sales. To close the gap, Mazda does intriguing things with software to make its cars drive better and react more quickly than even the most skilled driver can. Thus, G-Vectoring Control.
Before GVC, Mazda tuned its i-Activ all-wheel-drive system for what it believes is best-in-class winter driving, employing several dozen sensors to capture and respond to wheel-slip before even the driver notices it, again in a few milliseconds. In a series of tests in mountainous Colorado at the Mazda Ice Academy (photo inset), the Mazda CX-5 conquered hills and slippery slaloms better than competing SUVs. (Admittedly, on courses Mazda designed.)
Based on a day of driving several Mazda cars at Laguna Seca, Mazda makes a strong case that GVC is a feature you’ll want to have. It’s one more part of Mazda’s pursuit of Jinba Ittai, which roughly translates to “horse and rider as one,” or “oneness between car and driver.”
Mazda says G-Vectoring Control will first be available on the 2017 midsize Mazda 6 sedan and the compact Mazda 3. Mazda will outfit the entire line within “a couple years.” It’s not possible to retrofit current Mazdas. While it’s a software enhancement to the Mazda SkyActiv engine control module, there are also subtle tweaks to the suspension and steering. GVC will eventually be on all Mazdas, standard, and unlike the test cars, they’ll be always on (no off button).
An interesting possibility is what happens if other automakers want GVC to use on their cars. So far, Mazda hasn’t said if it would license GVC or a variant. There have been times in the past when one company had a technology everyone else wanted, such as Mitsubishi’s counter-rotating balancer shafts that reduced the vibration inherent in four-cylinder engines.