All-wheel-drive is a Subaru hallmark, but its standard AWD systems are primarily designed to give its cars good traction on normal roads when conditions become a little slippery, and not really intended for rough trails, steep hills, ice and snow.
This is where X Mode comes in. A feature in the Subaru XV, Forester and Outback, it helps drivers safely negotiate bad roads, slippery surfaces and inclines with confidence by constantly monitoring the traction available to each wheel and centralising control of the engine, transmission, brakes and other components.
To engage X Mode simply press the X Mode button near the gear shifter while travelling below 40 km/h. This engages up to three different controls:
- Engine Control Unit (ECU): On gravel or slippery surfaces the ECU will slowly provide acceleration to avoid sudden torque changes which helps avoid wheel slip and improve driveability.
- Traction Control Unit (TCU): The increases the AWD clutch pressure by around 25 percent, to help the front and rear wheels work together to improve traction.
- Vehicle Dynamics Control (VDC): This enhances the limited-slip differential control and improves traction by counteracting the differential rotation between the right and left wheels, particularly when turning.
X-Mode will disengage either function if you travel above 40km/h.
VDC also uses Hill Descent Control (HDC) to control brakes when coming down steep hills. This only intervenes below 20km/h and maintains a slow speed down the hill without you having to touch the brakes or accelerator, allowing you to focus on steering.
We tested this feature coming down Tasmania's infamous Jacob's Ladder, a steep, twisty and slippery road at Ben Lomond (above), one of the state’s highest mountains. The Outback we were in felt remarkably composed as it made its way down the hill at about 20km/h with absolutely no brake or accelerator input on our part.
HDC is based on speed data, not hill angle, so you can engage it at the flat top of a hill before you begin your descent.
X-Mode won't exactly give you the go-anywhere capability of bigger 4WD wagons, which have low-range gearing and greater ride height. But it will get an XV, Forester or Outback through many situations that few of their rivals can.
Explained: Subaru Driver Monitoring System