From Subaru... .
Advanced Subaru WRX STI
Research and Development from Nürburgring, Germany
Subaru released footage covering advanced research and development carried out at the Nürburgring’s racetrack in Germany, using a 2011MY Subaru WRX STI 4-door (sedan) test vehicle. Subaru has been using the famous Nordschleife course since 1992 for advanced R&D as well as tests of the WRX and WRX STI models. It is presented as a highlight of Subaru’s persistent effort to stretch vehicle performance to unprecedented levels.
The concept of the 2011MY WRX STI is “The Fastest WRX STI Ever.” At Subaru, the phrase “Fastest” refers to more than just top speed or maximum engine output. It implies driving with confidence. The WRX STI can be taken to its “fastest ever” performance by providing the driver with total driving control with confidence. Major upgrades to the 2011MY WRX STI focused on the chassis and suspension set-up, and tests at the Nürburgring demonstrated the supreme overall dynamics and linear behavior of the new STI. Tommi Mäkinen, the legendary four-time World Rally Champion, piloted the test vehicle for the development. He commented, “The car was controllable with precise and faithful handling even on tricky corners. I could easily predict the car’s behavior. That is exactly what Subaru is offering, confidence. As a result, the 2011MY WRX STI test vehicle recorded 7’55’’00, Subaru’s fastest lap time ever, which is 4 seconds faster than the previous fastest time recorded in 2004.”
The 2011MY WRX STI 4-door will go on sale world-wide this summer. Upgrades to the 4-door version will be carried over to the 5-door model.
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Subaru WRX STI
Since its introduction in 1994, the continuous evolution and development of the WRX STI is propelled by the strong support and expectations of thousands of enthusiastic customers and motorsports fans all over the world. These loyal customers strongly support Subaru’s fun-to-drive compact vehicle with superb performance through its unique power train, and unique combination of turbo-charged Horizontally-Opposed Boxer engine and Symmetrical All-Wheel-Drive (AWD) system.
Subaru persists in its philosophy of developing the ultimate driver’s car and embodying the essence of total driving control, from ordinary to extreme driving conditions. The Symmetrical AWD is the core technology to enhance such values in Subaru vehicles. With this philosophy in mind, Subaru’s performance icon, the WRX STI, received a full model change in 2007 to boast not only higher and exhilarating performance but also handling control. The controlled manner and accurate handling response will provide full confidence to the driver in all driving conditions. Even the most demanding drivers will feel they own an extraordinary driving machine. As Subaru’s performance flagship, the WRX STI defines Subaru’s view of AWD Sport.
Concept of 2011MY WRX STI
Based on the concept of “The Fastest WRX STI Ever”, the 2011MY was developed to deliver the maximum performance. Since the first generation WRX STI, the model has been developed to enhance its superior high performance with safety in all road conditions. The 2011MY WRX STI was tested to further refine its nature of a performance car in specific and severe conditions and on the circuits as well, including the Nürburgring racetrack. At Subaru, the phrase “Fastest” does not simply refer to the maximum top speed or engine output. It must come from the confidence a driver can get even on the limit. That confidence is derived from the linearity of the vehicle response to a driver’s input. The enhanced suspension improves precise handling and stability, offering predictable vehicle characteristics. Consequently, the 2011MY WRX STI delivers evolved total driving control in addition to ultra high performance.
Key enhancement for 2011MY
The 2011MY WRX STI further refined its “total driving control” ability by totally reviewed suspension system and lowered overall height. That enables drivers to control the car according to their intentions with improved, superior handling performance. Road holding capability was also improved, thus the driver can drive the car with complete trust in its cornering performance at high speed. In order to maximize the on-road performance, the 4-door sedan version was newly added in the line-up from the 2011MY. Its wide and low shape and large rear spoiler will surely appeal to enthusiasts.
For 2011MY, the overall suspension setup was revised to further improve accuracy and handling response, maneuverability, and road holding capability. In the front suspension, the rear-end arm bushes were changed to a pillow-ball type which is first ever adopted in the Subaru production models. This drastically improves toe stiffness as well as lateral stiffness in order to provide its evolved handling performance that is even more faithful to the driver’s steering control. The specifications of the sub-frame bushings of the rear suspension were also changed to improve toe and camber stiffness, resulting in increased vehicle responsiveness and road hugging capability. Specialized tuning of the damping force of both front and rear dampers provides secure road-holding ability. Changes to specifications of the front and rear coil springs, and stabilizers greatly improve roll stiffness. Due to those suspension refinements, the vehicle height was decreased by 5 mm for lower center of gravity to increase maximum lateral-G.
Nürburgring for Subaru
Subaru has a history of advanced research and development at the Nürburgring. Its constant challenges started in the late 1980’s for the evaluation test of suspensions and tires for the first generation Legacy. In 1992 Subaru first tested the Impreza WRX there. Since then, the Impreza WRX STI test vehicles have been running the 20.8 km (12.9 miles) Nordschleife course in the Nürburgring, which is well known as the most difficult racetrack in the world with more than 100 turns, and with 300 m (984 ft.) difference in altitude. The Nürburgring is the toughest and ultimate proving ground for all the auto manufacturers. As Subaru understands that all road conditions around the world are condensed in this racetrack, it has chosen the Nürburgring for many years in the development of the WRX STI in order to offer sheer excitement and unique driving feeling as a distinctive "Road Sport Model". Fast driving at the track requires a totally-balanced superior vehicle performance. Testing the vehicle at the Nürburgring also proves Subaru’s distinctive performance underpinned by its consistent development philosophy: Subaru pursues enjoyable, reliable, safe and secure driving with high performance. And that will certainly lead to driving with confidence.
History of development
The first challenge took place with the Impreza WRX test vehicle in 1992. Subaru engineers were all stunned at the severe characteristics of the course. The front part of the vehicle was heavily stressed especially on severe ups and downs. Subaru engineers fully realized insufficient abilities of brakes and suspensions, and learned the importance of further enhancement of the rigidity of the front. The vehicle, nevertheless, marked a lap time at 8’28’’93, thanks to its light weight body and excellent stability by Subaru’s authentic Symmetrical AWD system.
After the introduction of the WRX STI version in 1994, the test vehicle of WRX STI version III was tested at the course in 1996, marking 8’10’’75, 18 seconds faster than the 1992 recorded time. The engine output was increased with improved turbo charger and inter-cooler. To meet higher engine output, the transmission and brake system were also refined. A 4-piston front and 2-piston rear brake calipers were newly adopted, on the basis of the past testing experiences at the track. This enhancement of brake system eventually led to the adoption of the Brembo brake system.
The second generation WRX STI, introduced in 2000, featured new items which further enhanced driving performance: 225/45ZR17 tires, 6-speed manual transmission, new engine with variable valve timing control mechanisms and Brembo brake system. The model also dramatically improved its body rigidity to enhance collision safety performance. However, this resulted in a weight increase and the lap time of this model did not meet Subaru’s expectations.
In 2002 the WRX STI received a face-lift with superior aerodynamics, a finely-managed AWD system and new engine performance. The equal-length exhaust and Subaru’s first twin-scroll turbocharger increased the maximum output and torque. The newly-adopted auto mode in driver’s control center differential system optimizes torque distributions between front and rear axles. Thanks to those advanced technologies, this test vehicle recorded 8’06’’59.
The WRX STI evolved again in 2004. Wheel hubs, rims and tire width were enlarged. Helical type was newly adopted in the front limited slip differential gear to improve stability at cornering. An undercover helped improvement of aerodynamics. Enlarged inter-cooler increased maximum torque. Mainly due to the enhancement of chassis performance, the test vehicle finally broke the 8-minute barrier at 7’59’’41.
The third generation WRX STI was redesigned in 2007. One of the big topics in this model was the adoption of the totally new chassis system, “Subaru Dynamic Chassis Control Concept”. Newly developed double wishbone rear suspension offered superior road-holding ability by optimizing the geometry, including toe and camber angles and by regulating the lift motion. Subaru opted for the new 5-door package with a clear vision of what package is most appropriate to be competitive in the rally field, and what Subaru believes the ideal road sports car should be. Three key elements, “traction”, “response” and “stability”, were enhanced by its new chassis and package. Rainy conditions made the tests incomplete for the lap time comparable to the previous records.
The 2010 Challenge
Development of the 2011MY WRX STI focused on improved dynamics and precise handling with every aspect tested under extreme operating conditions including the toughest Nürburgring racetrack. To prove the development concept, “The Fastest WRX STI Ever”, Subaru chose the new 4-door sedan body for 2010 testing. Based on the 2011MY model, some potential future model items were added to this test vehicle, since Subaru positioned this challenge as one of stages in advanced research and development. Subaru evaluated the model’s performance, considering future product planning of the WRX STI.
The final challenge took place in April at the Nordschleife course. Subaru believes suspension performance is essential for high speed cornering with confidence. Therefore, the refinement of suspensions and chassis were mainly focused on this challenge as well as the development of 2011MY WRX STI. During testing, the car showed faster cornering speed. As a result, the test vehicle recorded 7’55’’00, the fastest lap time ever recorded in a Subaru, proving its development concept, “The Fastest WRX STI Ever”.
Subaru is fully committed to offer enjoyable, reliable and exciting driving with confidence to customers in its vehicle development philosophy. The aim of using the Nürburgring for Subaru is not to mark the fastest lap time but to develop vehicles that customers can drive faster yet safely with confidence even under extreme road conditions as typified by the Nürburgring. The refined suspension and new sedan body of the 2011MY WRX STI contributed much to this result, and this learning was accurately fed back to the production models.
Ideal driving on the Nürburgring racetrack is beyond measure by figures. It relies on experience and inspiration by the driver, too. Four-time World Rally Champion, Tommi Makinen, piloted the car. He has also been a longtime supporter of Subaru since he took the first driver’s seat of Subaru World Rally Team in 2002. Makinen explains, “The 2011MY WRX STI test car balances excellent stability and handling performance at a high level, thanks to its refined suspension. The car was really controllable with precise and faithful handling even on tricky corners. I could easily predict the next behavior of the car, that is, I confirmed its evolved total driving control ability. Subaru’s renowned Symmetrical AWD system also greatly contributed to this performance. The outstanding achievement is not only a tribute to Subaru’s continued and earnest efforts, but also evidence of confidence in driving a Subaru.”
For Subaru, the Nürburgring has been a place for self-discipline in its vehicle development. Subaru believes “Persistency is Power” and will continue to use the track to further pursue the development of vehicles which provides emotion, excitement and confidence to customers.
Major specifications of 2011MY WRX STI test vehicle:
- Overall length X width X height; 4,580 X 1,795 X 1,470 mm
- Wheelbase; 2,625 mm
- Engine type; Horizontally-Opposed 4-cylinder DOHC 16-valve turbocharged engine
- Displacement; 1,994 cc
- Transmission; 6 speed manual transmission
- Tires; 245/40 R18
Major added features to the test vehicle
<R205* model items> *R205 is a special edition for Japan market.
- Bigger turbocharger
- 6-pot brake calipers
- Flexible tower bar
- Front lip spoiler
<spec C* model items> *spec C is a special edition for Japan market.
- Bridgestone Potenza RE070 tires
- Aluminum hood
<Safety equipment>
- Full-bucket seat
- Roll cage
- 5-point safety belts
<Advanced items>
- Under cover
- Aluminum fenders
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