Contact: Rob Moran: 856-488-8615
Larkin Hill: 310-763-0929
SUBARU INTRODUCES 2004 IMPREZA® WRX® STi®
300-Horsepower “No-Compromise” Performance Model Challenges
The World’s Best Performance Cars
CHERRY HILL, N.J. – Subaru of America, Inc., the only car company that offers Symmetrical All-Wheel Drive
as standard equipment on every vehicle in its product line has introduced the long-awaited Impreza WRX STi for
2004, an ultra-high-performance all-wheel drive sedan. Based on the critically acclaimed Subaru Impreza WRX,
Impreza WRX STi is completely re-engineered to provide world-class sports car levels of acceleration, handling
and braking performance. Impreza WRX STi is the most powerful Subaru ever offered for sale in North America.
Impreza 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. 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. The engine is teamed exclusively to a 6-speed manual
transmission that has been specially designed to handle the high power and torque. Power is transferred to all four
wheels via a sophisticated Subaru All-Wheel Drive system designed to optimize performance in all conditions.
Introducing Subaru Tecnica International (STI)
STI stands for Subaru Tecnica International, the high-performance and motorsports subsidiary of Fuji Heavy
Industries Ltd. Subaru has been proving the performance and durability of its All-Wheel Drive technology in
World Rally Championship (WRC) competition since 1989.
Until now, STi-badged Subaru vehicles had been available only in select world markets. However, the success of
the Impreza WRX in the U.S. prompted strong (and vocal) demand from American consumers for an even more
extreme-performance version of this car. As a result, the U.S.-market Impreza WRX STi gives up nothing
compared to models offered in Europe, Japan and other markets and in some ways offers more performance.
For example, the 2.5-liter turbocharged powerplant is the largest displacement engine ever installed in a WRX
STi model and is exclusive to the North American market. This unique engine also provides strong torque
characteristics at both low and high rpm.
Impreza WRX STi/1
Rally Tested, Road Ready
The Impreza WRX STi benefits from the redesigned front and rear styling of the 2004MY Impreza line. The
expressive new design is the result of close consultation with Subaru STI engineers and the Subaru World Rally
Team to improve air resistance, optimize lift force balance, maximize engine cooling and provide Impreza models
with a bolder, more dynamic appearance.
In its exterior design, Impreza WRX STi leaves no doubts about its performance potential – a look that is equally
functional. The enlarged hood scoop in the aluminum hood feeds outside air to the intercooler that is significantly
larger than the unit found on Impreza WRX. A completely functional dual-plane rear spoiler – which appears to
be borrowed directly from the Subaru World Rally Car – helps reduce lift and improve stability at high speed.
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 semi-closed deck
engine block with forged aluminum-alloy pistons, forged high-carbon steel connecting rods and sodium-filled
exhaust valves. This advanced powerplant incorporates Subaru Active Valve Control System (AVCS) variable valve
timing technology to optimize the engine’s volumetric efficiency throughout the rev band. The high-boost
turbocharger produces up to 14.5 PSI of maximum boost. The large capacity intercooler includes a manually
operated water spray feature to provide additional cooling.
Driver Controlled Center Differential (DCCD)
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. In automatic mode, the electronically
managed continuously variable transfer clutch can vary the split ratio as needed to suit driving and road-surface
Automatic mode provides the best all-around performance for most drivers and circumstances, varying the
front/rear torque split automatically depending on driving conditions and driver input. The system responds to
acceleration, deceleration, cornering force and wheel slippage to determine the ideal power distribution.
In manual mode, DCCD allows the driver to vary the front-to-rear torque distribution to optimize All-Wheel Drive
performance to suit specific 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.
Impreza WRX STi employs a new Suretrac® limited-slip front differential and a mechanical limited-slip rear
differential. The Suretrac differential is a gearless unit that responds to a torque difference between left and
right front wheels to increase traction and reduce understeer.
Impreza WRX STi/2
Form Follows Function
Inside are several reminders that Impreza WRX STi is a special vehicle. The performance design front seats
feature substantial side bolsters, integrated head restraints and an embroidered “STi” logo. The seats are
upholstered in unique perforated blue Ecsaine® fabric with contrasting black knit bolsters, complemented by
expressive blue floor carpeting.
STI engineers also examined a wide range of measures to help reduce weight, eliminating items that did not
enhance performance. As a result, Impreza WRX STi does not include a standard sound system. However, this
model is pre-wired for an audio system, which is available as an optional accessory from Subaru dealers. Other
weight reduction measures include the use of lightweight rear window glass, aluminum front suspension control
arms and forged aluminum BBS wheels. Comfort features such as air conditioning, power windows, power door
locks and power mirrors – amenities that an owner cannot add after the sale – are included as standard equipment.
A revised STi instrument gauge cluster places a 9,000-rpm tachometer in the center, complemented by a 160-mph
speedometer, DCCD display, fuel and temperature gauges. All three primary gauges are trimmed with aluminum
rings. Red LED indicators and an illuminated “STi” logo in the tachometer reinforce the sporty driving
environment. Even the ignition key – inspired by a competition kill switch found in the Subaru WRC car – hints
at the special performance nature of this vehicle.
Offering a further preview the vehicle’s performance potential, all the gauge needles swing to their maximum
positions when the ignition is switched on, then fall back to their normal positions. The Subaru World Rally
Team-designed black leather-wrapped STi brand steering wheel provides a clear view to the gauges and features
red upper stitching and black lower stitching. The matching leather-wrapped parking brake handle with red
stitching is also unique to Impreza WRX STi.
A super-stiff Ring-Shaped Reinforcement Frame body structure with a hydroformed front subframe provides the
basis of the high-integrity Impreza platform. Compared to the standard WRX, the STi version has been lowered
by 0.4-inch, yielding a lower center of gravity. The 4-wheel fully independent suspension inherits technology
from the Impreza World Rally Championship competition car, but has been strictly optimized in WRX STi for
high cornering performance on paved roads.
Aluminum lower control arms help reduce unsprung vehicle weight and new inverted struts in the front and rear
suspension increase bending resistance for quicker and more consistent performance under hard cornering. A
rally-derived variation on the MacPherson-type strut, the inverted strut essentially functions like a conventional
shock absorber set upside-down and covered by another tube. The strength of the outer steel tube bears the
brunt of bending forces acting upon the strut under cornering, rather than the internal piston rod. The piston
rod operates in the lower portion of the strut tube (rather than the upper section), and the secondary upper tube
mounts to the inner fender where the piston rod would mount in a conventional strut. The piston’s stroke
remains consistent during hard cornering, helping to maintain the ideal tire-to-road surface contact pattern for
increased traction and cornering power.
Impreza WRX STi/3
The WRX STi employs a quicker steering ratio than the standard WRX model – 15.2-to-1 compared to 16.5-to-1
for the WRX. As standard equipment, Subaru equips WRX STi with 17 x 7.5-inch BBS aluminum-alloy wheels
and 225/45 ZR17 Bridgestone Potenza RE070 directional performance tires.
Brembo® Brakes with Super Sport ABS
Subaru has 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 extreme performance capability.
The front discs measure 12.7 inches in diameter and 1.2-inch thick and utilize four-piston, fixed-position calipers.
The rear discs are 12.3 inches in diameter and 0.8-inch thick and use two-piston, fixed-position calipers.
A combination of Electronic Brake-force Distribution (EBD) and a new Super Sport Anti-lock Braking System
(ABS) helps to reduce stopping distances and understeer compared to conventional ABS systems. Conventional
ABS systems control the rear wheels as a pair, reducing the braking force to both rear wheels when a loss of
traction is detected at either wheel. Super Sport ABS, using input from a lateral g-sensor, can control the braking
forces at each rear wheel independently, optimizing the braking ability during hard cornering, which reduces
understeer. EBD provides more precise control of braking pressure between the front and rear wheels based on
the vehicle load to improve stopping distances and stability.
Standard safety features include front seat head/chest side impact air bags (SRS), dual front airbags and 3-point
seatbelts. Front seat belts include electrically triggered pre-tensioners and force limiters. All 2004 Impreza models
feature a new safety pedal system designed to prevent injury to the driver’s lower limbs in the event of a serious
For additional information about Subaru of America, Inc. and Subaru vehicles, visit our media website at
About Subaru of America, Inc.
Subaru of America, Inc. is a wholly owned subsidiary of Fuji Heavy Industries Ltd. of Japan. Headquartered near
Philadelphia, the company markets and distributes all-wheel drive Subaru vehicles, parts and accessories through a
network of nearly 600 dealers across the United States. Subaru is the only car company that offers Symmetrical
All-Wheel Drive as standard equipment on every vehicle in its product line. Subaru has been the best-selling
import wagon in America for the past 21 years, based on R.L. Polk & Company new vehicle retail registration
statistics calendar year-end 2002.
Impreza WRX STi/4