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OPTICAL AND HEARING
2006 Subaru Impreza WRX STi - US model
.... not so attractive with its new corporate face
25th July, 2005
Back on the 17th June we published the story of Japan's 2006 Impreza. You can read that story here.
Now we have details of America's Impreza WRX for 2006. Australian specifications may differ. You can expect the 2006 Subaru Impreza line-up to be released in Australia in a few months time. That's when we'll learn of the Australian specifications. In the meantime, read on and see what Subaru has in mind for the American market.
The Impreza line is restyled with a new corporate face as its dominant feature. In addition the all-conquering WRX STI model is given several performance enhancements. On the safety front, all Impreza models for the American market gain the new dual-stage Subaru Advanced Airbag System.
Following an interior redesign for 2005, all Impreza models have been restyled for 2006 to reflect the new brand identity. The new Subaru signature front-end design for Impreza features a three-section mesh-type grille inspired by the company's aircraft heritage, plus boldly styled headlights with smoke-tinted lenses. All 2006 Impreza models are also identified by a new tail light cluster design.
The 2006 WRX STI is also distinguished by the lower-profile bonnet scoop from the standard WRX to aid forward visibility. Daytime running lights (DRL) are added to the safety roster to make the WRX STI more visible to other drivers. A new roof vane spoiler, inspired by the Impreza World Rally Championship competition car, contributes to stability at track speeds and reinforces the car's high-performance attitude.
The WRX STI received several significant chassis performance enhancements for 2005, including wider wheels. For 2006, the addition of a steering sensor input to the DCCD All-Wheel Drive system enhances power distribution response by more accurately relaying the car's cornering situation.
The WRX STI is based on the Impreza WRX platform but is completely re-engineered to provide even higher levels of acceleration, handling and braking performance that challenge the world's best sports cars. In its first year, the WRX STI won Road & Track magazine's "Best Car 2004" Reader's Choice Award, edging out several dedicated sports cars, including the Porsche 911 GT3.
The Impreza WRX STI is powered by a turbocharged and intercooled 2.5-litre DOHC boxer engine producing 300 horsepower at 6,000 rpm and 300 lb-ft. of peak torque at 4,000 rpm. Teamed exclusively to a 6-speed manual transmission, power is transferred to all four wheels by a sophisticated Subaru Symmetrical All-Wheel Drive system with Driver Controlled Centre Differential (DCCD) to optimise performance in all conditions.
Rally Tested, Road Ready
The WRX STI draws motorsports technology directly from Subaru expertise in World Rally Championship (WRC) competition and is designed to appeal to the most serious driving enthusiasts. STI stands for Subaru Tecnica International, the high-performance and motorsports subsidiary of Fuji Heavy Industries Ltd.
In its exterior design, Impreza WRX STI leaves no doubts about its performance potential - a look that is equally functional. The scoop in the aluminium bonnet feeds outside air to an intercooler that is significantly larger than the intercooler used on WRX models. The dual-plane rear spoiler - which appears to be borrowed directly from the Impreza World Rally Car - helps reduce lift and improve stability at track speeds. An aerodynamic underbody cover and the new roof vane spoiler contribute to enhanced high-speed track stability. Airflow is also managed via front side spoilers on the front bumper and STI-design aerodynamic side ground effects.
The front fascia features a four-beam headlight system with high-intensity discharge (HID) low beams. Distinctive STI fog light insert covers add to the no-nonsense look. Large diameter Brembo(R) brakes are clearly visible between the spokes of the 17-inch lightweight aluminium-alloy BBS wheels.
300-Horsepower Turbo Legend
The 2.5-litre horizontally opposed (Boxer) 4-cylinder engine is based on a specially reinforced semi-closed deck engine block with forged aluminium-alloy pistons, forged high-carbon steel connecting rods and sodium-filled exhaust valves. The Subaru Active Valve Control System (AVCS) variable valve timing technology helps provide strong torque characteristics throughout the engine's operating range.
The turbocharger produces 14.5 psi of maximum boost compared to 13.5 in the standard WRX. The large capacity intercooler uses a manually operated water spray feature to enhance intercooler efficiency during high-performance driving.
Symmetrical All-Wheel Drive With Driver Controlled Center Differential (DCCD)
The Impreza WRX STI is equipped with the brand's most performance-directed Symmetrical All-Wheel Drive system featuring Driver Control Centre Differential (DCCD). A planetary centre differential provides a performance-oriented 35 percent front/65 percent rear power split. Set in automatic mode, the electronically managed continuously variable transfer clutch can vary the torque distribution ratio as needed to suit driving and road-surface conditions.
Automatic mode provides the best all-around performance for most drivers and circumstances, varying the front/rear torque distribution automatically depending on driving conditions and driver input. The system determines the ideal power distribution in response to vehicle acceleration, deceleration, steering angle, cornering force and wheel slippage.
In manual mode, DCCD allows the driver to vary the front-to-rear torque distribution (up to 50/50 maximum) to optimise All-Wheel Drive performance for varying driving conditions. The driver first selects manual mode with a console-mounted button and then turns a thumbwheel on the centre console to select from among six levels of centre differential locking. Increasing the lock factor keeps more power at the front wheels, which the driver might want in certain driving conditions, on particular roads or to suit an individual driving style.
A helical-type limited-slip front differential and mechanical clutch-type limited-slip rear differential help to optimise power distribution side-to-side, helping to ensure that the inside wheels don't slip during cornering.
A super-stiff Ring Frame Reinforced body structure with a hydroformed front subframe provides the foundation for the high-integrity Impreza platform. Compared to the standard WRX models, the WRX STI is lowered by 0.4-inch to help yield a lower centre of gravity. The 4-wheel independent suspension inherits technology from the Impreza WRC competition car, but has been strictly optimised in the WRX STI for high cornering performance on paved roads.
Inverted struts used for the front and rear suspension increase bending resistance for quicker and more consistent performance under hard cornering. A rally-derived variation on the MacPherson-type strut, the inverted strut essentially functions like a conventional shock absorber set upside-down and encased by another tube. The strength of the outer steel tube bears the brunt of bending forces acting upon the strut under cornering, rather than the internal piston rod. The piston rod operates in the lower portion of the strut tube rather than the upper section.
The secondary upper tube mounts to the inner mudguard where the piston rod would mount in a conventional strut. The piston's stroke remains consistent during hard cornering, helping to maintain the ideal tyre-to-road surface contact pattern for increased traction and cornering power.
Aluminium front suspension lower control arms and aluminium rear suspension lateral links reduce unsprung vehicle weight. The standard BBS light-alloy wheels measure 17 x 8-inches and are equipped with 225/45 ZR17 Bridgestone Potenza RE070 directional performance tyres.
The quick-ratio steering system yields 2.6 turns lock-to-lock, and the steering rack uses a "cannon mount" for greater rigidity that improves on-centre response. A damper valve helps reduce kickback that the increased rigidity might cause.
Brembo Brakes with Super Sport ABS
Subaru equipped Impreza WRX STI with one of the most advanced and performance-optimised braking systems on the market today. The powerful Brembo Performance Brake System employs ventilated 4-wheel disc brakes to help ensure stopping power and consistency commensurate with the vehicle's high performance capability. The front discs measure 12.7 inches in diameter and 1.2-inch thick and utilise 4-piston, fixed-position calipers. The rear discs are 12.3 inches in diameter and 0.8-inch thick and use 2-piston, fixed- position calipers.
A combination of Electronic Brake-force Distribution (EBD) and the Super Sport Anti-lock Braking System (ABS) helps to reduce stopping distances and understeer compared to conventional ABS systems. EBD provides precise control of braking pressure between the front and rear wheels based on the vehicle load to improve stability and stopping distances. Conventional ABS systems control the rear wheels as a pair, reducing the braking force to both rear wheels. Super Sport ABS, using input from a lateral g-sensor, can control the braking forces at each rear wheel independently, optimising the braking ability during hard cornering to help reduce understeer.
The WRX STI conveys its performance attitude from the inside, as well. The driver grips a MOMO 3-spoke leather-wrapped steering wheel. Performance design front seats feature substantial side bolsters, integrated head restraints with "STI" logos. The seats are upholstered in unique perforated blue high-grip Ecsaine(R) fabric with contrasting black knit bolsters, complemented by matching blue door trim and blue floor carpeting.
The WRX STI instrument gauge cluster places a 9,000-rpm tachometer in the centre, flanked by the speedometer, DCCD display and fuel and temperature gauges. All three primary gauges feature aluminium trim rings. Red LED indicators and an illuminated "STI" logo in the tachometer reinforce the sporty driving environment. Previewing the vehicle's performance potential, all the gauge needles swing to their maximum positions when the ignition is switched on, and then return to their normal positions.
The standard automatic climate control system integrates cabin air filtration. The standard 140-watt AM/FM premium stereo plays through six speakers and includes a 6-disc in-dash CD changer. An engine immobiliser security system is standard equipment.
New Safety Technology for 2006
Front seat head/chest side impact air bags (SRS) are standard, and all Impreza models for 2006 get the new Subaru Advanced Frontal Airbag system. The driver's side air bag deploys according to the driver's proximity to the steering wheel, as measured by a sensor on the seat track. In the passenger side front seat, a sensor module detects weight on the passenger seat - first determining if it's occupied, and if so by a child or adult - to control air bag deployment. As part of the system, the dashboard features a new "Airbag" indicator light.
Front seatbelts integrate electrically triggered pre-tensioners and force limiters. A safety pedal system in all Impreza models is designed to prevent injury to the driver's lower limbs in the event of a serious front-end collision.
Once news on the Australian release is available, you can expect Next Car to publish details.