What is Symmetrical All Wheel Drive?

Symmetrical All Wheel Drive is a standard feature on every Subaru vehicle except for BRZ.  When many people think of all wheel drive (AWD), they think only of the benefits they would enjoy in snow, and ice (which are very considerable!)  But there are many more benefits too:
  • Your will have more control on perfectly dry pavement, especially during accident avoidance maneuvers.
  • You will have more control in rain. Especially in hydroplane conditions where tires start riding on top of the water.  Subaru All Wheel Drive (AWD) can pull power away from hydroplaning tires. 
  • You will have more control during a tire blow out; the all wheel drive system will pull power away from that wheel, reducing the likelihood of a skid. 
  • Your Subaru will have longer lasting tires because they wear more uniformly since all the tires are working to move the car forward.
  • You will have greater control while accelerating.  In front-wheel drive cars, the front wheels have to steer and grab for traction, creating a side-to-side tug in the steering wheel called torque steer.  In a rear wheel drive car, when the tires lose grip you experience a dangerous fishtail where the rear end starts whipping back and forth. 
  • You will experience quicker acceleration.  When you step on the gas, weight shifts from the front of the car to the back, lifting the front wheels off the ground.  Subaru AWD will move some of the torque to the rear, where more traction is available. 
How is "all wheel drive" different than "four wheel drive?" 

Four wheel drive systems distributes power or "torque" to each of the four wheels, regardless of whether any particular wheel has traction or not.  Subaru All Wheel Drive (AWD) moves torque to the wheels that have grip and away from the ones that are starting to slip.  Subaru's system can detect a slipping wheel in less than one revolution of that wheel. Once your Subaru detects slippage of a wheel, it pulls power away from that wheel, and redirects it to the wheels that still have traction.   
          


Does all wheel drive hurt fuel economy?
Yes and no. 
  • Yes, a tiny bit.  Before 1997, when some Subaru's were available with front wheel drive, the all wheel drive models were rated one mile less per gallon.  The all wheel drive hardware only adds about 150 pounds, so having all wheel drive is like having another person in your car. If you could have an extra "passenger" that kept you a lot safer under virtually every driving condition, you would want him with you all the time! 
  • No, compared to other all wheel drive vehicles, and even some front drivers.  The Subaru Impreza, at 36 mpg, is the most fuel efficient all wheel drive vehicle for sale in America.  What's more, it enjoys better fuel economy than many two wheel drive cars in its class. 


These models show the advantages of Subaru AWD over the systems from other brands. 

Truck Based 4WD    Vehicle Originally developed  Vehicle originally
found on pickups and    for front wheel drive and  then        developed for rear
     many SUV's                             AWD added                      and then AWD added. 


Advantages of Subaru AWD over other systems:
  • No buttons to push... you hit a patch of ice, it's too late to push a button activating all wheel drive.  Subaru's system is full-time. 
  • Because Subaru engineers its vehicles knowing that they will have all wheel drive, they can leave out heavy equipment that other manufacturers need to bolt on later.
  • Subaru AWD not only moves power from front axle to rear axle, but can also move power left to right, wheel to wheel.  That means you can have traction with only a single wheel and still get moving!  Many competing AWD systems can only move power axle to axle and not side to side. 
  • Subaru has over forty years of experience with all wheel drive.  You could say that Subaru has been engineering these systems before we put a man on the moon.  Subaru's system is elegant, simple, and battle-tested.

Why does Subaru call it symmetrical all wheel drive? 
If you cut a Subaru drive train in half, lengthwise, then each side would weigh the same.  They are essentially mirror images...symmetrical.