Subaru Impreza WRX STi reviews

2005 Subaru Impreza WRX STi Driving Impressions

No matter the model, the Subaru Impreza is extremely stable. All-wheel drive eliminates any hint of torque steer under hard acceleration.

Subaru Impreza RS, TS, and Outback Sport are powered by a 165-horsepower naturally aspirated horizontally opposed four-cylinder. WRX comes with a turbocharged and intercooled 2.0-liter engine that generates 227 horsepower, strong motivation to a 3100-pound car. WRX STi nails the needle to the peg with 300 hp from a 2.5-liter turbo and intercooled engine.

Four different types of all-wheel drive are used. Models with manual transmissions use a locking viscous center differential, while those automatic transmissions have Subaru's electronically controlled Variable Torque Distribution AWD. The WRX STi is equipped with a special heavy-duty six-speed manual gearbox and a driver-controlled center differential.

When the WRX was new, we called it "an absolute hoot to drive." But there's nothing like a generous dollop of horsepower in a compact chassis to twist the excitement dial over to the right and, with 300 horsepower, the STi boasts a power-to-weight ratio that humbles expensive sports cars and sports sedans.

Upon start up, the STi has the familiar and friendly Subaru vibrations, a distinctive feature of a horizontally opposed four-cylinder engine. The controls are light and the pedals well spaced; only a distinctly audible basso exhaust note hints that the STi is anything but an ordinary Impreza.

Once under way, the STi reveals that it is anything but. There's a tense feel to this engine even at part throttle, like it's ready to run. The heavy-duty gears in the transmission, exclusive to the STi, whine faintly, something Subaru didn't try to hide. Drive it over 3000 rpm and the turbo boost starts to rise, even with the gas pedal well off the floor, and the engine wants to surge the car forwards. The STi yearns to run. Slam the pedal to the floor and the STi grips and goes. The engine is louder than the WRX's but never gets raucous. It definitely does sound like a very serious Subaru.

(Technical stuff: Look under the hood. The intercooler, emblazoned with the STi logo, rests atop the engine like a crown. It cools the intake charge after it is compressed and heated by the turbocharger. The turbocharger is tucked behind and to one side of the engine. An unusual feature is a catalytic converter between the engine and the turbine. There are two more cats in the exhaust behind the turbo. The engine features dual overhead camshafts with four valves per cylinder with Subaru's Active Valve Control System variable valve timing, and solid lifters for reliable high-rpm operation. Throttle is electronic drive by wire.)

The WRX engine reaches its power peak at 6000 rpm and is redlined at 7000 rpm; maximum torque comes at 4000 rpm. Knowing how quickly this engine can rev to redline, Subaru has a buzzer that can be set to alert the driver to shift before the engine bumps up against its rev limiter. Gear ratios on the six-speed manual gearbox are well matched to the engine's torque curve, with second gear good to the high side of 60 mph. The shifter is quick and accurate and the transmission always willing to go to the next gear.

We had the opportunity to drive the STi on a road course. In all honesty, it's more at home there than on the highway, unlike most cars. The STi has all-wheel drive, like all Subarus, but its unique Driver Control Center Differential has a base 35/65 torque split between the front and rear. In automatic mode, an electronically managed continuously variable transfer clutch changes this ratio as needed to maintain the best ratio of grip between the front and rear wheels. The driver can choose, however, to vary this manually with a thumbwheel on the center console. We found it best, however, to let the computer do its thing. On the racetrack, it was infallible in divvying out the grip to the front and rear axles, which have l