The Good: Zero to sixty in less than five seconds; advanced handling technology; Brembo brakes. The Bad: Minimal soundproofing; stereo lacks MP3 compatibility. The Bottom Line: Sacrificing comfort for performance, the STi offers a great driving experience but little in the way of frills. 2005 Subaru Impreza WRX STiThe STi in the Impreza WRX STi's lengthy appellation stands for Subaru Technica International, Subaru's high-performance division. Technology, in the context of the Subaru WRX STi, is less about entertainment than driver control, which is appropriate, given its status as Subaru's high-performance flagship. With any WRX, particularly the STi, the entertainment is in the driving. This is not a car for the casual driver or the uncommitted nonenthusiast. It has ferocious power, and its suspension is optimized for high-limit cornering--at the expense of ride comfort and normal levels of interior noise. It's loud enough inside that, at speed, you won't hear the audio system all that well, but you'll be too busy driving to care. The Impreza-based WRX was a legend even before it became available in the United States, known mostly from magazine articles and video games. The 300-horsepower STi, introduced in 2003 as a 2004 model, has some significant tweaks for 2005. The styling remains the same, with rally-car fender blisters and the huge rear wing, although there's a new underbody cover for improved airflow and high-speed stability. There are significant upgrades to the steering, the suspension, and the Driver Controlled Center Differential (DCCD) all-wheel-drive system programming. The result is that Subaru's beast is better than ever, and its limits are even higher. At $33,020 base (including destination charge) or $33,938 as tested, it gives supercar performance and rally technology at a very good price. Driving-focused interior Compared with dedicated rally cars, the STi offers relative luxury. With good interior space for its size, it seats four comfortably. The trunk is also usefully large. As with other Imprezas, the STi's dash and center stack have been revised. The STi adds grippy Ecsaine fabric seat and door inserts, both in electric blue, to distinguish it from lesser Impreza models. The excellent driver control interface includes a three-spoke, leather-wrapped Momo steering wheel with a comfortably thick rim, a close-at-hand shift knob, and well-arranged metal and rubber pedals that facilitate easy heel-and-toe driving. Unlike serious rally cars, there is a very functional automatic climate-control system and an AM\/FM\/in-dash six-CD changer audio system, although the CD doesn't have MP3 capability.The steering column-mounted boost gauge would be better placed close to the windshield, where your eyes need to be when the gauge matters.Windows and outside rearview mirrors are power operated, but the seats are manual. That means less weight, as does the deletion of a significant amount of soundproofing material in the name of performance. The suspension calibration reinforces the performance angle, with firmer springs and shocks and less jounce and rebound travel than before. Wider BBS alloy wheels allow the tires to seat better than with last year's narrower rims, resulting in better cornering ability. Rear visibility is compromised by the large rear wing, and with the STi's speed capability, a close watch in the rearview mirrors is critical. But the wing is not a deletable option, since the suspension is calibrated for the downforce it generates.Heart of the beast Mechanical and electronic wizardry makes up the heart of the Subaru Impreza WRX STi. Like the base WRX, it uses a horizontally opposed four-cylinder boxer engine, but the STi's is larger in displacement, at 2.5 liters, and features the Active Valve Control System variable valve timing system for a broader torque band. Like the regular WRX, it's turbocharged, but it gets another pound of boost to 14.5psi, and air is fed to the intercooler via the extralarge scoop in the lightweight aluminum hood. Water can be sprayed on the intercooler to increase its effect during high-performance driving. Race-tech items such as forged alloy pistons, forged high-carbon steel connecting rods, and sodium-filled exhaust valves improve longevity. The result is a healthy 300 horsepower at 6,000rpm, with 300 pound-feet of torque at 4,000rpm--and a LEV emissions rating.It's not a particularly high-revving engine, which makes it easy to drive even in commute traffic, and with the $938 Performance Group 2B option, linkage to the six-speed manual gearbox shows a significant improvement upon earlier Subarus'. Not that much shifting is necessary with the STi's strong, wide power band. There is adequate but not excessive low-end power, with a strong rush from about 3,000rpm to just past the 6,000rpm power peak. The 2B package also includes a steering column-mounted boost gauge that's too small and too close to the driver to see well--under anything close to maximum acceleration, the driver's eyes had best be on the road ahead, not the instrument panel, which explains the red upshift light in the tach.As with all Subarus, power gets to the ground through all four wheels, all the time. The STi gets the most performance-oriented version of Subaru's symmetrical all-wheel-drive system with the DCCD. This system provides automatic fore-and-aft torque distribution, with a static 35 percent front\/65 percent rear distribution, or a driver-variable torque split as in pro rally cars. Programming for the DCCD has been revised this year to improve cornering ability in automatic mode. Additionally, both the front and rear differentials are limited-slip units for optimum side-to-side power distribution; the front differential is now a helical type for improved grip in tight corners.Controls let the driver switch torque to manual and adjust the fore-and-aft ratio of power distribution in the all-wheel-drive Subaru WRX STi. In high-performance driving situations, it works very well. Accelerating from 0 to 60 takes less than 5 seconds. The STi is set up for hard cornering, and the suspension tuning and extraquick steering mean that at speed, 100 percent of the driver's attention must be paid to driving. Yet it's docile in stop-and-go traffic and completely capable of living in the everyday world if you can stand the extra cabin noise.High-performance safety Like all Subarus, the Impreza WRX STi uses the ring-shaped reinforcement unibody construction to surround passengers with a strong safety structure. The hydroformed front subframe is designed for occupant protection, and dual front and front-seat-mounted side air bags are standard equipment. A high-performance car must stop as well as it accelerates, and the STi scores very well here. The Brembo brakes have 12.7-inch vented rotors and four-piston calipers at the front, as well as 12.3-inch vented rear rotors with two-piston calipers at the rear. Electronic brake-force distribution and the Super Sport antilock system, which uses a lateral-G sensor and controls each rear brake separately, provide fast, consistent stopping power. Traction control is done the old-fashioned way, with the right foot and steering wheel. Driver-adjustable headlight aiming is an interesting piece of standard equipment, letting the driver aim the lights higher for improved distance coverage or lower for normal traffic situations.