The high-performance capability of the 2004 Impreza WRX STi meshes with the brand's "Active Driving/Active Safety" design mandate. This means giving the driver control, maneuverability, security and the tools to help avoid hazardous situations.

Subaru believes driving pleasure and safety go together. Crisp handling and secure braking can make a vehicle more enjoyable to drive and therefore help keep the driver focused and involved with driving. With its unique Symmetrical All-Wheel Driving System, Impreza WRX STi may be one of the most driver-involving performance cars on the market.

That's why Subaru core technology - the Symmetrical All-Wheel Driving System - forms the basis of the Active Driving/Active Safety concept. The boxer engine provides a lower centre of gravity than other types of engine designs, contributing to more precise handling. The 4-wheel fully independent suspension helps keep the wheels in contact with all road surfaces, helping to maintain directional control on rough roads. All-Wheel Drive gives every Subaru a significant traction advantage over two-wheel drive cars (front- or rear-wheel drive) on both dry and slick roads.

The 2004 Impreza WRX STi takes the brand's core technology - the Symmetrical All-Wheel Driving System - to a new level of performance and safety. In terms of road grip and braking capability, the WRX STi is in a league with the world's best high-performance sports cars.

The Safety of Clear Visibility
Active safety in a Subaru starts with visibility - seeing and being seen. Optimal outward visibility supports driver judgment and helps reduce driver fatigue. The standard pump-type driver seat height adjuster and a tilt-adjustable steering column help the driver find an ideal driving position to ensure best visibility.
A driver who can judge a car's length, width, and mass will feel a heightened sense of maneuverability and control. The distinct outlines of the fenders and new character lines in the 2004 Impreza hood also give the driver a strong sense of the front-end positioning.

The compact Subaru boxer engine also benefits collision safety, because it allows more crush room in front and on the sides. Subaru vehicles are designed to allow the engine and transmission to slide under the car along the floor tunnel in a severe frontal collision, helping to prevent intrusion into the passenger compartment.

Using frameless door glass and paying special attention to pillar size and positioning gives Subaru vehicles an open and airy greenhouse for maximum visibility. On the 2004 WRX STi, a fin on the driver's side windshield wiper helps keep the blade stable at higher speeds.

Passenger Protection: Rings of Safety
The high-integrity Impreza platform provides Impreza WRX STi with a greater degree of passive safety. Performance in one type of collision cannot accurately predict how a vehicle will perform in other types of collisions. Passenger vehicles must provide protection in real-world offset-type collisions (impact concentrated on one side of the vehicle), meet government standards for a full frontal impact and offer side impact protection.

All Subaru models use an innovative Ring-Shaped Reinforcement Frame body structure that ties together the side sills, centre pillars and roof supports to form a structural ring around the passenger compartment. This structure provides Impreza models with outstanding protection in a wide variety of collisions including frontal offset, side and rear.

Front and rear crumple zones help manage impact energy in a collision. Impreza models employ a hydroformed U-shaped front sub-frame that helps absorb impact energy in an offset collision. Placed under the front side frames, the sub-frame forms part of a two-stage crash structure that helps control and disperse impact energy and prevent cabin deformation.

The hydroforming process applies extremely high water pressure to shape steel tubing in a mold. The resulting frame members provide high strength without excess weight or build complexity.

Using tailored blank welding for the B-pillars and side sills produces high-strength structural pieces with lower weight than single pressings. A "tailored blank" is made from several pieces of sheet steel, usually of differing thickness and properties. These are joined by laser welding and then stamped into the desired shape in a die. The ability to place steel pieces of optimal thickness and grade precisely where they are needed helps to build in structural rigidity without adding excess weight.

Dual reinforcement beams in the front doors and a rear door beam provide protection in side impacts. Rear side frames adapted from the larger Subaru Legacy feature a reinforced shoulder area that increases side impact protection. Strengthened door latches and their engagement parts both contribute to side impact safety and also improve door operation. The hood is designed to minimize the chance that its rear edge will contact the windshield in an offset collision.

Consistently a "Best Pick"
Subaru has consistently received high ratings in crash tests by independent testing organizations such as the Insurance Institute for Highway Safety (IIHS). The IIHS conducts demanding 40-mph frontal offset crash tests. The current-generation Impreza model has achieved the highest possible rating ("good") for crashworthiness in the IIHS test, also receiving the IIHS "best pick" designation.

Restraint Systems
Standard passive safety features in every 2004 Impreza model include 3-point seatbelts for all five seating positions and dual front airbags. Impreza WRX and WRX STi models add standard head/chest side impact airbags located in the front seatbacks to help provide optimal protection regardless of seat position.
The front 3-point seatbelts feature electrically triggered pre-tensioners and force limiters. These systems work together to gradually restrain the occupants and absorb the impact energy of a frontal collision. In the event of a moderate-to-severe frontal collision, the seatbelt pretensioners - operating simultaneously with the front airbags - cinch the front seatbelts to help restrain the driver and front passenger in their seats. Next, the mechanically operated torsion bar force-limiters extend the belts to reduce the belt forces on occupants' torsos. The seatbelt mechanism also absorbs energy through internal deformation.

All Subaru models for 2004 are equipped with upper head impact protection. The 2004 Impreza models also introduce a new safety brake pedal system that helps to reduce injury to the driver's lower limbs by yielding in the event of a serious front-end collision. Impreza sedans feature integrated headrests for all rear seat positions. Additional standard safety equipment includes the (LATCH) uniform child restraint anchorage system (Lower Anchors and Tethers for CHildren) for use with compatible child safety seats. All Subaru sedan models include a self-illuminating internal child safety trunk release.

New Super Sport ABS for WRX STi
The new Brembo® Performance Braking System with 4-Channel/4-Sensor Super Sport ABS provides both active and passive safety benefits.

For secure braking, all current Subaru models are equipped with a standard 4-channel/4-sensor Anti-lock Brakes System (ABS) to help preserve steering ability under hard braking by preventing wheel lock-up. Electronic Brake-force Distribution (EBD) - featured on all 2004 MY Impreza models and select other Subaru models - enhances braking performance and stability by actively optimizing braking force between the front and rear wheels according to the vehicle's load.

Exclusive to the 2004 Impreza WRX STi, a new Super Sport Anti-lock Braking System (ABS) helps to reduce understeer and enhance stability under hard braking. This advanced system also helps reduce stopping distance when cornering compared to conventional ABS. Super Sport ABS uses a lateral g-sensor, an additional input that gives the system the ability to control rear brake pressures individually under ABS operation. Standard ABS systems control the rear wheel brake pressures together. If an inside wheel begins to lose traction, as it could under simultaneous hard cornering and braking, Super Sport ABS fine-tunes control at each rear wheel independently to help maintain stability through the curve. By increasing brake pressure on the outside rear wheel, overall braking force to the front wheels is reduced, providing more available traction for cornering and reducing understeer.