2006-2007 Subaru Impreza WRX STi

Pros :
- All-wheel-drive handling.
- Barely noticeable turbo lag.
- Great interior trim with high level of standard equipment.
- Very, very fast.
- Superb brakes, suspension, engine...a cut above the base WRX.

Cons :
- Front end still not to everyone's tastes.
- Sub-compact rear passenger room.
- Hard ride quality.
- Dealer price mark-ups.
- Sky-high insurance premiums.

Interior :

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Press Coverage :
Subaru has restyled its Impreza line for 2006 and in addition given the all-conquering 300-horsepower WRX STI model several performance enhancements. On the safety front, all Impreza models gain the new dualstage 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 grill 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 lamp cluster design. The 2006 WRX STI is also distinguished by the lower-profile hood 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-liter 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, the engine can propel the WRX STI from zero-to-60 mph in under five seconds. Power is transferred to all four wheels by a sophisticated Subaru Symmetrical All-Wheel Drive system with Driver Controlled Center Differential (DCCD) to optimize performance in all conditions.
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 aluminum hood 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 brakes are clearly visible between the spokes of the 17-inch lightweight aluminum-alloy BBS wheels.
The 2.5-liter horizontally opposed (Boxer) 4-cylinder engine is based on a specially reinforced semiclosed deck engine block with forged aluminum-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.
The Impreza WRX STI is equipped with the brand’s most performance-directed Symmetrical All-Wheel Drive system featuring Driver Control Center Differential (DCCD). A planetary center 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 optimize 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 center console to select from among six levels of center 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. Subaru equipped Impreza WRX STI with one of the most advanced and performance-optimized 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 utilize 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.
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 and embroidered “STI” logos. The seats are upholstered in unique perforated blue high-grip Ecsaine 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 center, flanked by a 160-mph speedometer, DCCD display and fuel and temperature gauges. All three primary gauges feature aluminum 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 immobilizer security system is standard equipment.
Subaru of America

One look at the numbers demonstrates that it outperforms its capable, though less-costly, little brother on every front. The first thing you'll feel is the ultra-wide powerband, courtesy of both larger cubes and variable valve timing. The close-ratio six-speed means you can keep the engine on boil without having to flog it, and it's smooth right to its 7000-rpm redline. Steering is light, reasonably quick, and has adequate, if not race-carlike, feel. It understeers sooner than we'd hoped, but grips like Spiderman--anything over 69 mph through our slalom test is way impressive. The brakes are solid, easy to modulate, and highly resistant to fade.
Comparisons to the Mitsubishi Evolution are inevitable, and we're happy to make them, with these caveats: Although we tested both with the same driver and timing gear, we believe the surface on which we ran the Evo to be slightly grippier. This won't affect acceleration (these are AWD cars, so little wheelslip is involved), but would give the Mitsubishi a handling and braking advantage. Also, our STi was a barely broken-in, preproduction model. So, while these numbers are highly representative--and amazingly close--they're not 100 percent like-kind. A pure apples-to-apples comparo is in the works.
Overall, the Evo suspension is tuned more aggressively: It turns in sharper and rolls less. The STi is obviously a handler, but more supple, more tossable, and easier to live with on nasty road surfaces. The Subaru is better for high-speed work--less nibbling at uneven road surfaces--and the sixth gear makes cruising much more relaxed. We expected the STi's power advantage would prove it quicker, but the Evo's more aggressive gearing and manic boost levels served up slightly better acceleration numbers. Braking is about a wash.
Motor Trend

The WRX STI remains the ultimate Impreza. It gets the new nose and revised taillights along with reshaped side sills, a roof spoiler just above the rear window and an underbody diffuser. Complaints about poor visibility in last year's STI also prompted a return to a standard-size WRX hood scoop. Sad, but true.
The 2006 STI rides an eighth of an inch lower on structurally stronger inverted struts that provide better control under load. Subaru also added a steering angle sensor and a mechanical differential to the Driver Controlled Center Differential (DCCD). Subaru says the extra diff improves the system's responses to changing terrain while the new steering sensor betters the computer's ability to determine where you're trying to go and how best to get you there. The improvements also allowed Subaru's engineers to change the standard torque split from 35-to-65 front-to-rear to 41-to-59 and give the DCCD system a greater range of torque distribution. They also gave the six-speed manual transmission carbon-plated synchros in fourth, fifth and sixth gears for smoother engagement and improved durability. Its 2.5-liter 300-hp flat four remains unchanged, although liquid-filled engine mounts have been added to reduce vibration.
The STI is a monster in the dirt, accelerating ferociously and providing the kind of unfiltered feedback you need to go fast. Its ability to accelerate around a turn is just plain scary. It's definitely the most capable STI we've ever driven.
Edmunds.com

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History:
2003-2005 Subaru Impreza WRX STi
2,500 cc / 300 hp / 300 lb-ft / 3263-3298 lbs / 0-60 mph 4.7 sec.

2001-2002 Subaru Impreza WRX STi (not sold in USA)
1,994 cc / 280 hp / 275 lb-ft / 3146 lbs / 0-60 mph 4.8 sec.