Bell & Colvill Subaru News
New Subaru Impreza WRX STI 4-door Saloon is back...
25th September 2010
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 6-speed manual transmission and the exclusive Multi-Mode Driver Controlled Centre Differential (DCCD) version of Subaru’s Symmetrical Full-time All-Wheel Drive system.
The WRX STI is equipped with advanced dynamic control systems, including Subaru Intelligent Drive (SI-DRIVE) and a Multi-Mode Vehicle Dynamics Control (VDC) system, which 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.
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 feedback from both owners and enthusiasts, as well as 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 responsive 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 and 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 vs. 20 mm in front and 19 mm vs. 18 mm in rear. Spring rates have increased by 15.6 percent in front and 53 percent in the rear.
New standard 18-inch Enkei aluminum wheels feature high-luster paint and weigh 8kg less than the previous standard wheels. 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. With Intelligent mode selected, SI-DRIVE improves fuel efficiency and provides a more relaxed throttle response curve, making it useful for commuting in traffic, for example.
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
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, utilizing 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 disc brakes with Super Sport anti-lock (ABS) and Electronic Brake-force Distribution (EBD). Front discs measure 326 mm (13.0 inches) in diameter and use 4-piston, fixed-position calipers; the 316 mm (12.6 inch) rear discs use 2-piston, fixed-position calipers. 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.
Tech Spec:
PERFORMANCE
Max. output (DIN) PS @ rpm 300 @ 6,000
Max. torque (DIN) Nm @ rpm 407 @ 4,000
Max. speed mph 158 (in 6th gear) 155 (in 6th gear)
Acceleration (0-62 mph) sec. 5.2
Fuel consumption*
Urban mpg 20.0
Extra-urban mpg 33.6
Combined mpg 26.9
