Subaru has created a niche market for their all-wheel-drive 2015 Forester SUV, XV Crosstrek crossover, Legacy sedan, Outback wagon, WRX and WRX STI performance models. But they don’t have a “one type fits all” approach with their multi-purpose vehicles. They all come standard with Symmetrical All-Wheel Drive, but each vehicle gets a “tailored” version of Subaru’s Symmetrical All-Wheel Drive to fit a particular powertrain or model.
Subaru doesn’t adapt AWD components to a front- or rear-wheel drive vehicle, they develop all their multi-use vehicles around Symmetrical All-Wheel Drive. Many automakers do adapt their AWD system to fit a front-drive configuration and thus they function passively, transferring torque away from the main drive wheels only when they slip. The competition equipped with such systems essentially operate in two-wheel drive when there is no slippage. They can be better than front-drive car, but don’t provide the “full-time” benefits and road handling ability that a true full-time All-Wheel Drive system like Subaru’s does.
Why does Subaru offer four different versions of AWD? All versions of Subaru Symmetrical All-Wheel Drive distribute torque to all four wheels all the time, and each is tailored to the specific vehicles engine, suspension and transmission. Each reduces the load on each wheel and reducing and even helping to prevent tire slip, especially on slippery or loose surfaces. Here’s the different Subaru versions and which vehicle it’s tailored to.
2014 Impreza 2.0i and 2014 XV Crosstrek models with 5-speed manual transmission; 2014 Legacy, Outback and Forester models with 6-speed manual transmission and 2015 WRX with 6-speed manual transmission. Here’s how it works. A viscous-coupling locking bevel-gear center differential built into the transmission case distributes torque 50:50 front-to-rear. Slippage at the front or rear wheels causes torque to transfer (up to 100%) to the opposite set of wheels.
Active Torque Split
Here’s the models that use it, All 2014 models, and the 2015 WRX, that are equipped with the Lineartronic continuously variable transmission (CVT). How does it work? An electronically managed continuously variable transfer clutch actively manages torque distribution in response to driving conditions, acceleration, deceleration and cornering. Slippage at the front or rear wheels causes torque to transfer (up to 100%) to the opposite set of wheels.
Variable Torque Distribution (VTD)
Here’s the models that use it, 6-cyl. Legacy and Outback models and the Tribeca. How does it work? An electronically controlled, continuously variable hydraulic transfer clutch works with a planetary gear-type center differential to control torque distribution between the front and rear wheels. Under most conditions, VTD uses a 45:55 torque split, with the rear-wheel bias contributing to handling agility. VTD responds to driving conditions to continually optimize torque distribution on all road surfaces. Slippage at the front or rear wheels causes torque to transfer to the opposite set of wheels.
Driver Controlled Center Differential (DCCD)
It's exclusive to the 2015 WRX STI and we covered it extensively here.
In addition to its Symmetrical All-Wheel Drive, Subaru also uses Vehicle Dynamics Control (VDC) to Augment their vehicles AWD capability. It comes standard on every 2014 and 2015 Subaru model except the rear-drive BRZ that gets VDC and rear-wheel traction control. The VDC system uses sensors “to compare where the vehicle is heading to where the driver is steering it.” The system will take corrective action to keep the vehicle on course if needed, and can apply brake pressure automatically and reduce torque to the wheels that need it.
Subaru uses four versions of Symmetrical AWD for their all-wheel-drive 2015 Forester SUV, XV Crosstrek crossover, Legacy sedan, Outback wagon, WRX and WRX STI performance models. These four AWD versions are what sets Subaru vehicles apart from the competition.
Other Subaru AWD stories of interest.
- 5 driving instructors test AWD capabilities of the most popular mid-size SUVs
- USAC tests AWD capabilities of most popular mid-size SUVs [video]
- Watch 2014 Subaru XV Crosstrek Hybrid pull out stuck UPS truck
Watch all-new 2015 WRX STI video as it uses its DCCD all-wheel-drive system in the dirt.