The Subaru Impreza III Hatchback WRX STI 2.5, produced between 2007 and 2011, represents a high-performance iteration of Subaru’s popular compact car. This model, part of the third-generation Impreza (GD/GG chassis), specifically the GE/GH hatchback variant, was engineered to deliver exhilarating performance and rally-inspired handling. The WRX STI 2.5 occupied the top echelon of the Impreza lineup, offering a significant upgrade over the standard Impreza and the less powerful WRX models. It was primarily marketed towards driving enthusiasts seeking a capable and engaging all-wheel-drive vehicle.
Technical Specifications
| Brand | Subaru |
| Model | Impreza |
| Generation | Impreza III Hatchback |
| Type | WRX STI 2.5 (330 Hp) AWD |
| Start of production | 2007 |
| End of production | 2011 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Hatchback |
| Seats | 5 |
| Doors | 5 |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 4.8 sec |
| Acceleration 0 – 62 mph | 4.8 sec |
| Acceleration 0 – 60 mph | 4.6 sec |
| Emission standard | Euro 4 |
| Power | 330 Hp @ 5400 rpm |
| Power per litre | 134.3 Hp/l |
| Torque | 470 Nm @ 3400 rpm / 346.65 lb.-ft. @ 3400 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | EJ257 |
| Engine displacement | 2457 cm3 / 149.94 cu. in. |
| Number of cylinders | 4 |
| Engine configuration | Boxer |
| Cylinder Bore | 99.5 mm / 3.92 in. |
| Piston Stroke | 79 mm / 3.11 in. |
| Number of valves per cylinder | 4 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Turbocharger, Intercooler |
| Valvetrain | DOHC |
| Engine oil capacity | 4.3 l / 4.54 US qt | 3.78 UK qt |
| Coolant | 7.7 l / 8.14 US qt | 6.78 UK qt |
| Trunk (boot) space – maximum | 538 l / 19 cu. ft. |
| Fuel tank capacity | 60 l / 15.85 US gal | 13.2 UK gal |
| Length | 4415 mm / 173.82 in. |
| Width | 1740 mm / 68.5 in. |
| Height | 1475 mm / 58.07 in. |
| Wheelbase | 2620 mm / 103.15 in. |
| Front track | 1495 mm / 58.86 in. |
| Rear (Back) track | 1500 mm / 59.06 in. |
| Minimum turning circle | 10.6 m / 34.78 ft. |
| Drive wheel | All wheel drive (4×4) |
| Number of gears | 6 gears, manual transmission |
| Rear suspension | Several levers and rods |
| Front brakes | Ventilated discs |
| Rear brakes | Disc |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Tires size | 245/40 R18 |
| Wheel rims size | 18 |
Powertrain & Engine Architecture
The heart of the Impreza WRX STI 2.5 is the 2.5-liter EJ257 boxer engine. This horizontally-opposed four-cylinder engine benefits from a closed-deck block design for increased strength and durability, crucial for handling the increased boost pressure from its turbocharger. The EJ257 utilizes multi-point fuel injection and a dual-scroll turbocharger, contributing to improved throttle response and reduced turbo lag. The engine’s DOHC (Dual Overhead Camshaft) valvetrain, with four valves per cylinder, further enhances its breathing capabilities. The 6-speed manual transmission, a hallmark of the STI, features close ratios optimized for performance driving. The transmission is robust, designed to withstand the engine’s substantial torque output.
Driving Characteristics
The WRX STI 2.5 delivers a raw and engaging driving experience. The 330 horsepower and 346 lb-ft of torque, combined with Subaru’s symmetrical all-wheel-drive system, provide exceptional grip and acceleration. The close-ratio 6-speed manual transmission allows for precise gear selection, keeping the engine within its optimal power band. Compared to the standard Impreza or even the WRX, the STI offers significantly sharper handling and a more responsive feel. While the ride quality is firmer due to the sport-tuned suspension, it provides excellent body control and minimizes body roll during cornering. The turbocharger does introduce some lag at lower RPMs, but the power delivery becomes forceful and linear as the engine builds boost.
Equipment & Trim Levels
The WRX STI 2.5 was generally well-equipped, though options were available to further enhance the driving experience. Standard features typically included sport seats with bolstered support, a leather-wrapped steering wheel, and a premium audio system. The interior featured aluminum pedal covers and unique STI badging. Optional extras often included a sunroof, navigation system, and upgraded Brembo brakes. The STI trim level was positioned as the premium offering, and as such, it lacked the more basic features found in lower Impreza trims.
Chassis & Braking
The Impreza WRX STI 2.5 boasts a reinforced chassis and a sophisticated suspension system designed for high-performance driving. The suspension utilizes inverted MacPherson struts at the front and a multi-link setup at the rear. Stabilizer bars are thicker than those found on lesser Impreza models, further reducing body roll. The braking system features ventilated disc brakes on all four wheels, providing ample stopping power. Many STI models were equipped with Brembo brakes as an option, offering even greater stopping performance and fade resistance.
Market Reception & Comparison
The Impreza WRX STI 2.5 was generally well-received by automotive critics, praised for its performance, handling, and all-wheel-drive capability. It was often compared to rivals such as the Mitsubishi Lancer Evolution. While the STI offered a more raw and visceral driving experience, some critics noted its firmer ride quality and less refined interior compared to some competitors. Fuel economy was also a concern, typical for a high-performance vehicle. Compared to the standard Impreza and the WRX, the STI represented a significant price premium, reflecting its enhanced performance and features.
Legacy
The Subaru Impreza WRX STI 2.5 remains a popular choice among enthusiasts and collectors. The EJ257 engine, while known for its potential for modification, is generally considered reliable when properly maintained. Common maintenance items include regular oil changes, timing belt replacements, and inspection of the turbocharger. The STI’s all-wheel-drive system and robust drivetrain contribute to its longevity. Today, well-maintained examples of the Impreza WRX STI 2.5 command a premium in the used car market, reflecting its status as a performance icon and a testament to Subaru’s rally heritage. The car continues to be a favorite for track days and spirited driving, and its enduring popularity ensures its place in automotive history.
