Test Drive: Subaru WRX STI adds power, new technology

Tag : automatic control valves

For tuner-car or rally enthusiasts, the undisputed answer is aresounding "Yes!"
The all-new 2008 STI is the third generation of Subaru'sprofessional, rally-bred supercar. Developed by Subaru TecnicaInternational, the motorsports division of Subaru, theall-wheel-drive STI is a high-performance version of the ImprezaWRX.
Nearly every major mechanical system in the STI is unique, as areas some of its interior appointments. With destination charges, theSTI starts at $35,640.
For 2008, Subaru optimized the STI's powertrain for betterperformance and a higher degree of driver-selectable control. Its2.5-liter, turbocharged and intercooled, 4-cylinder, boxer-styleengine now has a Dual Active Valve Control System (Dual AVCS) andSubaru's Intelligent Drive (SI-Drive) system.
Dual AVCS controls valve timing on both the intake and exhaustvalves. Subaru says this helps eliminate the traditional compromisebetween low-end torque and high-rpm horsepower, while aiding fueleconomy and emissions.
SI-Drive allows the driver to alter the car's drivingcharacteristics. A console-mounted dial offers three settings,varying from one that offers optimal fuel economy to one thatprovides lightning-quick throttle response.
The STI now achieves 305 horsepower, a gain of 12 over last year'smodel. Peak torque of 290 ft-lbs. remains the same, but now arrivesat 4,000 rpm -- 400 rpm earlier -- for improved response. Theturbocharger produces up to 14.7 pounds per square inch of boost,compared to 11.9 in the 224-hp WRX.
Under hard throttle, the STI's response is lightning-quick, whilethe driver is kept busy working up through the gears of the 6-speedmanual transmission. In testing the STI, Car & Driver magazinerecorded a 0-60-mph time of 5.1 seconds, and a quarter-mile time of13.6 seconds at 102 mph. Top speed is electronically limited to 151mph.
During DriveTime's test-drive week, the STI showed it can be easilydriven with restraint in congested city conditions. Light use ofthe throttle results in an experience not too far removed from astandard Impreza.
The EPA rates the STI's mileage at 17 mpg city and 23 mpg highwayusing premium gas.
The STI features a Driver Control Center Differential (DCCD)version of Subaru's all-wheel-drive system. DCCD offers threeselectable automatic performance modes in addition to manualdifferential-locking settings. The normal power split is 41 percentto the front wheels and 59 percent to the rear; for more agilehandling. DCCD now integrates the vehicle stability and tractioncontrol system, which also has three driver-selectable positions.
A new double-wishbone suspension with special tuning helps ensurethe STI's tires stay firmly planted to the road even when the caris tossed through corners. Ride comfort is greatly improved overthe previous model, with no jarring effects from a stiffsuspension.
The Brembo brake system employs ventilated four-wheel disc brakesthat do their job very well.
Starting with the Impreza's new hatchback bodywork, the STI gains astealthy look with bulging fenders and quarter panels, rear-mountedspoiler and other aerodynamic aids. The hood scoop, front brake airintakes and engine heat outlets are functional.
The five-passenger STI comes with special front seats designed withtight side bolsters and integrated head restraints. The upholsteryis Alcantara cloth with leather trim. The instrument clusterfeatures a 9,000-rpm tachometer and 160-mph speedometer, along withindicators for the driver-selectable functions.