Tossed straight into the middle of a blizzard-hit Colorado winter, CarAdvice is spending some time this week in assessing the Mazda i-Active all-wheel-drive system on slick ice and snow - not just in isolation, but also against the competition from Honda and Subaru.
To prove its mettle, Mazda has prepared a test facility specifically for the task. The Japanese car maker is confident that, over the course of the day, we'll see its CX-5 with i-Active AWD run rings around the Subaru Forester and Honda CR-V.
“The goal for the Mazda i-Active AWD system is to preserve the precise, intuitive feeling you expect from Mazda, even on low-grip surfaces,” says Dave Coleman, development engineer for Mazda USA.
Coleman says the system should function "seamlessly, with no input from the driver", while having a negligible impact on fuel economy.
“i-Active AWD is directly aimed at trying to eliminate some of the traditional disadvantages of an on-demand AWD system,” Coleman says. "It’s a predictive system, rather than reactive, because it anticipates tyre slip and activates AWD before that happens.”
Mazda has calibrated the i-Active system to work with various information feeds that are coming from the hundreds of sensors mounted in various areas of the CX-3, CX-5 or CX-9. This data is then used to help the AWD system be more predictive rather than reactive.
“There is so much data now that flies around the vehicle’s electronic system, and that is the strength,” says Coleman. “We feed that data into the management system so we can better assess the activation of the AWD system.
"Think about it: your vehicle reads the outside temperature, it knows your windscreen wipers are on and how fast they are travelling, it can read incline, steering effort versus angle, individual wheel speed, accelerator pedal position, brake fluid pressure and steering angle.”
Coleman goes on to explain that if the outside temperature is reading -10 degrees, for example, it’s fair to assume there will be ice on the road and therefore a slippery surface.
“Steering effort changes with available grip for example. The sensors already in place for the electric steering system give us a very accurate picture of available grip, even off throttle. After studying human perception, we found a gap between the amount of front tyre slip we can recognise through wheel speed sensors and the threshold a driver can recognise through the steering wheel," Coleman said.
"This gives us a control window to manage front tyre slip, while maintain that sense of our vehicles being fun to drive."
Critical to the intelligence of the Mazda system is active torque coupling. “It’s electronically activated so it can respond instantly and at any speed,” Coleman says.
“Predicting the need for torque transfer does no good if you can’t deliver it when needed. Instant reaction allows rear torque output to be controlled more precisely. Further, to eliminate delay from mechanical backlash, the Mazda system runs a small pre-load under most conditions.”
One thing Mazda and Subaru agree on is the reason most buyers opt for an AWD vehicle: "buying AWD is a security decision,” Coleman says.
“It’s about peace of mind and we don’t want buyers having to trade that decision off against factors like fuel economy or price. With our system, weight impact is minimised, fluid losses are minimised, and for the comparative size of the vehicles, we have the lightest AWD system on the market.”