What makes us different, makes us better
If you want to be a leader, you need to get in the game early. You don't become a leader by finishing second. And you don't become better by being the same. We have been fine-tuning our symmetrical AWD technology for over 40 years. This wealth of experience has led to a vehicle line up with the widest range of AWD systems offered by any one manufacturer. We take AWD seriously because we know that - if the goal is making cars safer, more capable and more fun-to-drive, in all possible driving conditions, with higher levels of confidence - 4 is better than 2.
Traction dictates how well a vehicle accelerates, how it handles curves and inclines, how quickly it stops and how it performs on uneven or slick surfaces. Capturing the most traction possible is key to optimizing vehicle performance, handling and proactive safety in a variety of conditions. Here are some reasons why 4 is better than 2 in this respect - and why Subaru symmetrical full-time AWD is a better 4.
Although a 2WD system can be front-wheel drive (FWD) or rear-wheel drive (RWD), FWD is most often found in everyday passenger cars and is the least expensive to produce. Its strength is in normal driving conditions, where the front wheels are required only to manage the demands of gentle cornering and mild power delivery. When demands intensify, the weaknesses of FWD become quickly apparent:
- Under strong acceleration, weight transfer sees the nose of the vehicle lift, which can lead to torque steer and a loss of traction
- In corners, FWD vehicles tend to understeer: The driver turns the wheel in the direction of the corner, but the high demands of cornering and inefficient power delivery can lead to a loss of traction and less stable, less direct cornering
- In slick or loose conditions, FWD can suffer greatly because all of the demands are on the front wheels for power delivery, cornering and braking - with significantly less traction available
Result: A drivetrain and a vehicle that is inherently unbalanced much of the time.
A part-time (on demand) AWD system operates in 2WD mode (FWD on most vehicles) most of the time and automatically switches to AWD when conditions warrant. It's also best under normal driving conditions when there's not much work for the wheels to do. However, when conditions require power to be sent to the other wheels, challenges arise:
- The power-splitting mechanism of the on-demand AWD system is generally limited to helping you get going when starting to accelerate in a low-traction situation
- When driving in slick conditions at higher speeds or on a very long and curvy road, the on-demand system can struggle to keep pace with the circumstances
- If conditions change suddenly, the on-demand system may not be able to react quickly enough to avoid potential hazards
Result: This type of drivetrain is typically also unbalanced and limited in AWD mode when you need it most.
While part-time (on-demand) AWD systems only respond to a loss of traction, full-time AWD systems are always engaged and always active, making them the most effective and safest solution for all possible driving conditions. These systems are also particularly adept at handling unpredictable driving conditions, when immediate response is critical. Here are some key differences that make full-time AWD the best choice:
- Full-time AWD maximizes available traction right from the start by sending power to all four wheels and maintaining power when road surfaces take a turn for the worse - this ensures high levels of control, stability and overall confidence
- Even in everyday driving conditions, less power is sent to each individual wheel compared to a FWD or a part-time (on-demand) AWD system, so the wheels are less likely to slip and lose traction
- Full-time AWD provides the added security of being able to instantaneously handle a change in traction or a change in direction
- The latest full-time AWD systems are more lightweight, more efficient and more reliable than ever before - and Subaru symmetrical full-time AWD is the example that proves this rule
Result: An inherently more balanced, safer, more entertaining and more confidence-inspiring drivetrain.
Full-time AWD = Full-time Benefits
More confidence = more fun to drive
Sending power to all four wheels gives a vehicle more grip, more predictable handling, better agility and greater control. These advantages result in a stronger connection between the road and the car, an increased sense of confidence for the driver and more sheer enjoyment behind the wheel. Subaru symmetrical full-time AWD is engineered to deliver confidence in motion - in all seasons and on all roads, especially the twisty and challenging ones.
More traction + more stability = greater safety
Subaru's symmetrical full-time AWD is just that - full-time. It is always engaged and is, therefore, better equipped to handle unexpected circumstances. It distributes power among all four wheels in a balanced manner that creates greater stability and captures more traction, outperforming FWD or part-time (on-demand) systems every time. Even when one wheel hits a slippery or loose surface, all four wheels remain powered to maximize every opportunity for traction and increased levels of control.
All-road, all-weather capability = more freedom
Rain, sleet, snow and ice have the very real potential to sideline even the best-laid plans. But Subaru symmetrical full-time AWD has the capability to make quick work of more challenging driving conditions, including gravel roads and even more adventurous trails where drivers of FWD or part-time (on-demand) AWD vehicles would never dare venture.
Smarter design = better economy + more durability
Some AWD systems are considered overly complex and not all that reliable or economical. But these criticisms are more suited to truck-like 4WD systems - 4WD is not like AWD. Subaru symmetrical full-time AWD is not like run-of-the-mill AWD, either. The engine is mounted in-line with the drivetrain to deliver power to all four wheels directly and efficiently without additional components required. A smarter design with fewer components means reduced complexity, greater durability, increased fuel-efficiency (comparable to FWD on most models) and lower maintenance costs.
Why symmetry makes all the difference
While other manufacturers bolt AWD on to existing vehicle designs, Subaru started from the ground up to engineer a total system with every component designed to support AWD. The engine, transmission and centre differential are compact, efficient and set along the centre line of the vehicle for near perfect balance side-to-side, smoother power delivery and greater stability, especially in the corners.
Start with a horizontally opposed ("boxer") engine with a short overhang for greatly enhanced agility. Its flat profile also enables a lower centre of gravity for a more planted feeling, better handling and improved stability overall.
Make this engine compact and lightweight. Link it to a compact, lightweight transmission. Connect both to a compact, lightweight differential.
Place the engine/transmission/differential package longitudinally along the centre line of the vehicle for improved efficiency and ideal balance, left to right.
Set this package over the front axle to make the vehicle less nose-heavy, thereby reducing dive under sharp braking and minimizing yaw, the tendency of a vehicle to spin.
Employ an independent, long-travel suspension system with equal-length axle shafts, front and back, to eliminate torque steer and maximize tire contact with the road, no matter the road conditions.
The Subaru AWD Systems
The truth of the matter is, one size never fits all. This is why Subaru doesn't offer just one type of symmetrical full-time AWD system, but rather a variety of different systems that fall into four broader categories. Each system is tailored and tuned to suit the individual characteristics of the vehicle and driver:
This system is used for all models equipped with manual transmissions, excluding the WRX STI. It delivers the sporty satisfaction of quick shifts combined with an AWD system that makes the most of the available traction at all times. This system also features an efficient layout with a viscous-coupling limited slip centre differential that maintains a 50/50 front/rear torque split for optimum torque distribution, near neutral handling and surefooted performance.
This system employs a multi-plate transfer clutch that maintains a 60/40 front/rear torque split and uses a range of sensors to automatically adjust this split on-the-fly as conditions warrant, creating more predictable handling. The system that's linked to all Subaru models (excluding WRX) equipped with the Lineartronic® Continuously Variable Transmission (CVT), the Active Torque Split AWD places the focus on ease of operation, fuel efficiency and reliability.
Linked to the Sport Lineartronic® CVT and exclusive to the WRX, this AWD system delivers sportier performance and superior efficiency all at once. The centre differential adjusts front/rear torque split from 45/55 in normal conditions (for a sportier rear-biased feel) up to 50/50 when the weather worsens or the road conditions deteriorate (for maximum traction). The viscous self-locking rear differential maintains stability when more torque is sent to the rear wheels, ensuring the perfect balance of control and fun.
As it's a purebred high-performance car, it follows that the Subaru WRX STI would feature the ultimate in high-performance AWD systems. The DCCD allows the driver to adjust the centre differential locking (through one manual and three automatic modes), varying the torque split from 41/59 front/rear to 50/50 to suit the mood and the conditions. The AWD system also includes a helical-type front differential and a TORSEN® rear differential, creating a triple-differential set-up that is completely unique in the industry.