The Subaru Technica International (STI) S209, is currently undergoing final assembly in Kiryu, Japan, and will receive upgrades in terms of its looks, power, handling, aerodynamics and driver engagement.
Because it is receiving engine modifications and bodywork alterations that in total require it to be homologated for the US by STI, the S209 is thus considered the first “STI-built” Subaru to be sold in the US.
The S209 carries on a high-performance tradition that dates to STI-built models that were exclusive to the Japanese domestic market – the S201 (2000) through to the S208 (2018).
Designed with a focus on high-performance driving, the S209 draws inspiration and tech transfer from STI’s most formidable track machine - the WRX STI Nürburgring Challenge racecar, which won the SP3T class at the 2018 24 Hours of Nürburgring, marking the fifth time STI dominated the SP3T class at the grueling endurance race.
Like the Nürburgring Challenge racecar, the S209 wears an expanded wide-body exterior treatment, which extends the vehicle’s overall width to 1,839mm (+43mm) over the standard WRX STI.
The bulging fenders accommodate +15mm wider front/rear tracks and exclusively developed 265/35 Dunlop SP Sport Maxx GT600A tyres fitted to lightweight 19 x 9.0 forged BBS alloys to help it achieve a maximum grip of over 1.0g.
Vents on the front fenders provide additional engine cooling, while vents on the rear fenders rectify air turbulence to reduce drag.
The Brembo brakes, with cross-drilled steel rotors and six-piston monoblock front calipers and dual-piston monoblock rear calipers with upgraded high-friction pads provide the stopping power with improved fade-resistance.
Beneath the S209’s broader body are specially developed Bilstein dampers, stiffer coil springs, a 20mm rear stabilizer bar and pillow-type bushings for the front/rear lateral links.
Additionally, reinforcements have been provided to the front crossmember and rear subframes and just like the Nürburgring racecar, it has a flexible front-strut tower bar and flexible front/rear draw stiffeners.
The tower bar, unlike a conventional rigid bar, is split and joined with a pillow ball joint in the center to be longitudinally mobile while helping laterally stiffen the body of the car.
This results is optimum tyre grip during lateral moments combined with compliant ride during longitudinal moments.
Meanwhile, the draw stiffeners apply tension between the body and cross member to optimize chassis flex, improving stability when cornering and delivering better ride, handling and steering response.
Other Nürburgring racecar tech that trickles down to the S209 are the front, rear and side under spoilers; front bumper canards; carbon-fiber roof panel and rear wing.
The legendary EJ25 2.5-litre Boxer engine has been thoroughly reworked to provide 341hp thanks to the bigger HKS turbocharger with larger turbine and compressor that ups the pressure by 6% and 8% respectively, compared to the WRX STI.
In this instance, maximum boost has been increased to 18psi (16.2psi for the WRX STI) and to handle the pressure are lighter and stronger forged pistons and connecting rods.
Midrange torque, too, gets a notable bump, up 10% at 3,600rpm, delivering higher corner exit speeds when driving on track.
For ultimate driver engagement, the S209 comes exclusively with a close-ratio six-speed manual transmission that routes power to a full-time Subaru Symmetrical All-Wheel Drive system with front/rear limited-slip differentials, a Driver Controlled Center Differential (DCCD), Active Torque Vectoring and Multi-Mode Vehicle Dynamics Control.
A recalibrated SI-Drive system offers three modes of Intelligent (I) for improved fuel economy and smoother power control, Sport (S) for optimized power balance between response and control and Sport Sharp (S#) for achieving the best acceleration times.
The STI engineers recommend Sport over Sport Sharp for circuit driving, as the less aggressive throttle map allows for greater driver control.
To feed more air to the EJ25, the S209 uses a high-flow intake system featuring a new intake duct, induction box with conical air filter, silicone turbo inlet duct and, a nod from the 2004-07 WRX STI, an intercooler water spray system that lowers intercooler temperature via manually operated steering-wheel paddles.
More air demands more fuel, so the S209 receives a new high-flow fuel pump, larger fuel injectors and an STI-tuned engine control module.
High-performance mufflers deliver 17% less airflow resistance while larger hand-polished stainless-steel exhaust tips – 101mm in diameter – deliver an aggressive appearance and acoustics.
The S209 receives multiple tweaks to elevate it from other STI sedans. An STI badge replaces the traditional Subaru star cluster on the center of the D-shape steering wheel, which is wrapped in Ultrasuede with silver stitching, a treatment that carries over to the lid of the center console storage box.
Also, an S209 serial number badge resides on the center console, and S209 badges adorn the passenger-side dash and the headrests of the Recaro front bucket seats, which feature new silver-hued inserts.
Outside, special S209 badges are affixed to the front grille and fenders as well as the rear decklid.
Around 200 units of the STI S209 will be built and have been earmarked exclusively for the U.S.
Available exterior colour/BBS wheel combinations will be WR Blue Pearl/gray wheels and Crystal White Pearl/gold wheels.