NEW YORK, New York – Subaru today introduced a new 4-door version of the Impreza WRX STI performance flagship. This will be the first time that the WRX STI has been offered both the 5-door and 4-door body styles in the same model year. In addition to the new styling, the 2011 WRX STI features significantly revised suspension tuning and lighter 18-inch wheels for even sharper handling.
The WRX STI has been continuously improved since its introduction. Thorough and painstakingly detailed chassis development, including testing on Germany’s famed Nurburgring racetrack, has resulted in the best-handling Impreza WRX STI models Subaru has ever offered.
“The continuous evolution and development of the WRX STI is driven by strong, loyal and vocal support from thousands of enthusiastic owners of this exciting high-performance vehicle,” said Katsuhiro Yokoyama, president and CEO of Subaru Canada, Inc. “The 2011 WRX STI will expand the appeal of this iconic performance model to a wider range of driving enthusiasts.”
The 2011 Impreza WRX STI models arrive in Subaru dealerships late this summer.
Performance Evolution
The 2011 WRX STI continues as the ultimate-performance Subaru with its high-boost 305 horsepower turbocharged/intercooled Subaru Boxer engine teamed with a close-ratio 6-speed manual transmission and the exclusive Multi-Mode Driver Controlled Centre Differential (DCCD) version of Symmetrical full-time All-Wheel Drive.
The WRX STI is equipped with advanced dynamic control systems, including Subaru Intelligent Drive (SI-DRIVE) and the Multi-Mode Vehicle Dynamics Control (VDC) system that features a track performance-optimized mode. Hill Holder, featured on all Impreza models equipped with a manual transmission, can momentarily prevent the vehicle from rolling backward when being driven away from a stop on an incline.
All-New 4-Door Wide-Body Design for 2011
The new WRX STI 4-door design is based on a “wide and low” concept that gives the car an aggressive road presence. Like the wide-body design already used for the 5-door WRX STI, the new 4-door WRX STI features widened front and rear track dimensions and wider, more pronounced front fenders and rear quarter panels. The design maintains a consistent flow from front to rear bumper, creating a distinctive identity and a sense of stability.
In front, the 2011 WRX STI features sharpened bumper corners to accentuate the “wide and low” profile. A jutting lip spoiler with three-dimensional detailing emphasizes the cars’ sporty intent and the headlights now have a silver-painted inner housing. A newly designed front grille with a black inset and blacked-out Subaru floating wing set off the headlights’ shape to give the entire front end a more powerful appearance.
For the WRX STI 4-door sedan, new wider fenders are stretched out on the side more than the tail lamps, and this accentuates a look of stability. A striking larger rear spoiler was exclusively designed for the STI 4-door. The new details contribute to an improved drag coefficient, and the rear spoiler design contributes to stable high-speed handling and achievement of zero lift. STI sedan also features its own version of Subaru’s polished stainless steel quad-tailpipe exhaust, with tailpipe diameter enlarged to three inches.
New WRX STI Chassis Tuning for 2011
The Subaru WRX STI was already a highly optimized performance machine. Changes in chassis tuning for 2011 reflect both feedback from owners and enthusiasts, and the brand’s commitment to keeping this model at the peak of the segment’s performance offerings. The fundamentals remain the same as before, but specific tuning results in reduced body roll, more neutral handling response and higher lateral-G capability.
The WRX STI delivers ultra-crisp handling along with everyday ride compliance. High-tensile-strength steel is used at key structural points and the suspension-mounting areas. Inverted struts used for the front suspension provide high bending resistance for quicker and more consistent performance under hard cornering. Aluminum front lower L-arms reduce unsprung vehicle weight.
Major changes to suspension tuning for the 2011 WRX STI include a lowered ride height and new pillow-ball bushings in front as well as stiffer bushings for the rear subframe that supports the double-wishbone suspension—these improve camber and toe stiffness. Both the front and rear suspension systems employ higher-rate springs and thicker front and rear stabilizer bars than the 2010 model: 21 mm versus 20 mm in front and 19 mm versus 18 mm in rear. Spring rates have increased by 15.6 percent in front and 53 percent in the rear.
New standard 18-inch aluminum wheels feature high-luster paint and weigh 8 kg less than the previous standard wheels. These wheels further reduce unsprung vehicle weight. Dunlop SP600 245/40R18 summer performance tires are used with the standard and optional wheels.
SI-DRIVE Gives WRX STI Driver More Control
Exclusive to the WRX STI models, Subaru Intelligent Drive (SI-DRIVE) technology allows the driver to tailor the car’s driving characteristics by choosing from among three selectable modes—Intelligent, Sport and Sport Sharp—using a rotary dial on the centre console. SI-DRIVE alters vehicle performance characteristics by regulating the Engine Control Module (ECM) and by fine-tuning the Electronic Throttle Control system. For example, with Intelligent mode selected, SI-DRIVE provides a more relaxed throttle response curve, making it useful for commuting in traffic.
Sport mode provides quick throttle responses and powerful, linear acceleration, making it ideal for everyday sporty driving. In Sport Sharp mode, SI-DRIVE modifies the engine’s electronic throttle mapping to deliver super-quick throttle response and put down the power sooner.
Multi-Mode DCCD All-Wheel Drive with Three-Mode Vehicle Dynamics Control
As before, the 2011 WRX STI is exclusively equipped with the Multi-Mode Driver Controlled Centre Differential (DCCD) version of Subaru Symmetrical full-time All-Wheel Drive. The system employs planetary-type differential gears with a nominal 41:59 torque split. A mechanical limited-slip centre differential augments an electronically controlled centre differential to enhance torque transfer performance. A steering sensor input enhances torque transfer response by accurately relaying the car’s cornering situation. A helical-type limited-slip front differential and a TORSEN torque-sensing limited-slip rear differential optimize side-to-side power distribution, helping to prevent the inside wheels from slipping during cornering.
The DCCD AWD system features three automatic modes. Auto mode provides the best all-around performance for most drivers and circumstances, varying the front/rear torque distribution automatically in response to vehicle acceleration, deceleration, steering angle, cornering force and wheel slippage. The Auto (-) mode makes less use of the centre limited-slip differential (less locking factor) and holds the torque bias to the rear more frequently, which yields more handling-oriented steering characteristics. For driving on slippery surfaces, such as gravel or snow, the Auto (+) setting tightens the LSD. In manual mode, DCCD offers six levels of centre differential locking, allowing the driver to vary the front-to-rear torque distribution (up to 50:50 maximum) to optimize AWD performance for varying driving conditions.
The Vehicle Dynamics Control (VDC) stability and traction control system is standard on all Subaru models for 2010. It is important to note that, in Subaru vehicles, traction control plays a second line of defense against wheel slip after AWD torque distribution. In contrast, some other all-wheel drive systems lack the performance advantage of a locking centre differential and rely solely on traction control to redistribute torque away from slipping wheels.
Exclusive to the WRX STI, the Multi-Mode VDC system offers the driver three settings: VDC Normal, Traction and Off. The Normal setting provides the highest level of system engagement, using traction control (TCS) and VDC. The Traction setting is more performance-oriented, employing less-restrictive VDC and disengaging the engine torque-reduction control. The Off setting disengages the VDC and the traction control functions.
Also exclusive to the WRX STI, the Brembo Performance Brake System uses ventilated 4-wheel Super Sport anti-lock (ABS) disc brakes with Electronic Brake-force Distribution (EBD). Front discs measure 326 mm in diameter and use 4-piston, fixed-position callipers; the 316 mm rear discs use 2-piston, fixed-position callipers. Taking input from a lateral g-sensor, a steering angle sensor, a yaw sensor and a brake pressure sensor, Super Sport ABS can control the braking forces at each rear wheel independently, which optimizes braking ability during hard cornering to help reduce understeer. In contrast, conventional ABS systems control the rear wheels as a pair, reducing the braking force to both rear wheels equally.
Sporty, Spacious and Versatile Interior
New for 2011, the WRX STI interior is finished in black and silver to highlight its sporty design. The colour of each metallic part was unified to dark metallic and sharp silver. Trim panels, steering wheel air bag cover and steering wheel switches are now dark cast metallic.
The standard tilt and telescopic steering wheel is a 3-spoke, leather-wrapped design embossed with the STI logo. The wheel features control switches for Bluetooth hands-free phone function. The WRX STI models are equipped with standard aluminum-alloy pedal covers and driver’s footrest. Performance-design front seats integrate the backrest and head restraint into a single structure. The instrument panel electroluminescent gauges use indicator needles that sweep the gauge faces upon engine startup.
The compact layout of the double-wishbone rear suspension helps to minimize intrusion into the cargo area, providing a wide and deep luggage compartment. In 5-door models, the wide and flat load floor can accommodate two Tour-size golf bags with the rear seat backs in the upright position. In the 4-door sedan, which is 165 mm longer than the 5-door, the extra space provides for a larger, deeper trunk that can accommodate three Tour-size golf bags. A 60/40 split-folding rear seat further boosts cargo capacity and convenience, and the 4-door also features a rear seat fold-down centre armrest.
Standard amenities that help make the WRX STI an excellent everyday driver include an AM/FM stereo with single-disc CD player that features Bluetooth audio streaming and hands-free calling, iPod control capability, a USB port, a 3.5 mm auxiliary input jack and SIRIUS satellite radio capability. A vehicle security system with engine immobilizer is standard, as well. All WRX STI models come pre-wired for SIRIUS satellite radio.
Subaru Safety
Electronic Brake-force Distribution (EBD) provides precise control of braking pressure between the front and rear wheels based on the vehicle load to improve stability and stopping distances. Brake Assist analyzes the force and stroke on the brake pedal and increases hydraulic boost to provide enhanced emergency braking, also activating the ABS system early if needed.
Every Impreza is built around the proven Subaru Advanced Ring-Shaped Reinforcement Frame body structure with front and rear crumple zones, and all feature standard side-curtain airbags. The Subaru Advanced Frontal Airbag System (SRS) includes front seat side impact air bags. In the passenger side front seat, a sensor module detects weight—first determining if the seat is occupied, and if so by a child or adult—to control air bag deployment. As part of the system, the dashboard features an “Airbag” indicator light. There are 3-point seatbelts for all seating positions, including front height-adjustable seatbelts with electrically triggered pre-tensioners and force limiters.
