Subaru Impreza WRX STiIn March 2002, the WRX touched down on North American soil, offering consumers a unique intercooled and turbocharged high-performance vehicle, minus the high sticker price.
Enthusiasts consider the WRX a rally car tamed for the streets. Impressively, the Subaru Impreza WRX has out-performed all sales expectations and posted a new sales record, while Subaru of America Inc. recorded its third best year in sales history.
Until now, STi-badged Subarus have been available only in select world markets with North America being excluded from the list. With the WRX now firmly in our grasp, there's been a growing demand from enthusiasts for a more aggressive performance version of the WRX. Subaru was quick to respond by offering a North American version of the WRX STi.
Subaru Technica International (STi), a high-performance subsidiary of Fuji Heavy Industries Ltd., has a proven track record using Subaru's all-wheel-drive system in World Rally Championships since 1989.
EngineA turbocharged/intercooled 2.5-liter boxer engine powers the WRX STi, while the standard WRX comes equipped with a 2.0-liter engine. The 2.5-liter engine is the largest ever offered in a STi model and exclusive to the North American market. Horsepower figures check in at an impressive 300 hp at 6000 rpm with 300 lb-ft of torque at 4000 rpm.
Along with more displacement, Subaru's Active Valve Control System (AVCS) and its version of variable valve timing, along with sodium-filled exhaust valves, bring a 73-hp and 83 lb-ft of torque improvement over the standard WRX powerplant.
An oversized intercooler and manual water spray located above the intercooler reduce heat transfer and increase intake efficiency. The STi block is die-cast aluminum with a semi-closed open deck cylinder design, while the standard WRX comes with an open deck design. The engine is coupled with a newly introduced six-speed transmission with a final-drive gearing of 3.90:1.
Along with the all-wheel-drive system, the WRX STi is equipped with DCCD (driver control center differential). In automatic mode, the computer, depending on the owner's driving condition, automatically adjusts the front/rear torque split. In manual mode, the DCCD system allows the driver to custom tailor torque distribution using a control wheel located on the STi's center console, transferring as much as 65% of available torque to the rear wheels to alter handling characteristics.
The STi version utilizes a new Suretrac limited-slip differential on the front and mechanical limited slip for the rear. Suretrac units differ from the standard WRX viscous locking differential because of a gearless setup, which responds to wheelspin between left and right wheels, offering increased traction and reduced understeer.
The WRX STi's aesthetics have been fully redesigned with aid from Subaru STi engineers and the Subaru World Rally Team. Working side by side with the engineers, the designers addressed a number of areas on the STi, such as improving air resistance, optimizing lift force balance and providing the Impreza a bolder, more dynamic appearance compared to previous models. The STi offers a comparably larger hood scoop than the WRX, which increases airflow to the often heat-soaked intercooler. STi side ground effects, integrated front side bumper diffusers and a functional dual element spoiler are strikingly similar to the ones used on Subaru's rally car, offering increased stability at high speeds. Smoke-tinted HID headlights and exclusive STi foglight covers set the STi apart from its counterparts.
Equipped with a lateral-g sensor, the STi's Super Sport ABS can independently control the braking force of each wheel unlike conventional ABS, which controls the rear wheels as a pair. The advantage to the electronic brake-force distribution (EBD) can be felt in hard cornering situations, allowing for less understeer and more stability. The STi is equipped with Brembo four-piston calipers in the front with a 12.7-in. rotor; the rear utilizes a two-piston caliper with 12.3-in. rotor.
In comparison to the standard WRX, the STi has been lowered 0.4 in., yielding a lower center of gravity. A sport-tuned suspension and inverted struts are all inherited technology from the Impreza World Rally Championship competition cars, which have been successful throughout the years.
Circuit racers and casual weekend warriors will appreciate the improved steering ratio over the standard WRX. The STi's 15:1 ratio-compared to 16.5:1 on the WRX-increases responsiveness when taming tight turns.
As standard equipment, Subaru equips each STi model with a set of gold 17x7.5-in. BBS aluminum alloy wheels wrapped in 225/45ZR-17 Bridgestone Potenza RE070 summer tires.