Subaru Cosworth Impreza STI CS400 will be released in limited edition of just 75 units. The car is the result of one of the most interesting collaborations in recent times. This is the first Cosworth-developed road car since 1996, when Ford Escort Cosworth was discontinued. STI CS400 will be thrill of a lifetime for few happy owners.

Subaru Cosworth Impreza STI CS400 is one of the most powerful hatchbacks on the market. It is powered by 2.5 litre four-cylinder turbocharged Boxer engine developing 400ps. Thanks to Cosworth's extensive Formula 1 experience, this engine produces 33 per cent more power than originally from the factory. The power is put on the road through six-speed manual gearbox. The acceleration is astonishinrg – 3.7 seconds to 100 km/h and top speed of 155 mph ( electronically limited). The car covers a quarter mile in 12.75 seconds at a terminal speed of 107 mph.

All main components in the car are specially tuned from Cosworth. It features revised turbo system, sports exhaust, suspension, brakes and wheels and some improvements to the exterior and interior to make STI CS400 even more exclusive.

Subaru Coswroth Impreza STI CS400 is developed for UK market, so the car is in right-hand drive form. It is available in a choice of three exterior colours - Spark Silver, Dark Grey and San Remo Red.

STI CS400 is priced at £49 995 on-the-road.

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2.5-liter Boxer Engine Develops 33 per cent More Power

There is a relatively small engine under the bonnet of Cosworth Impreza, but it is pumped up by a huge turbocharger. It is marque's famous horizontally-opposed, all-aluminium Boxer engine. The flat-four powerplant is removed from the car, entirely revised by Cosworth and mounted back.

The Boxer engine in STI Cosworth features twin overhead camshafts per cylinder bank (DOHC) plus an Active Valve Control System (AVCS) to deliver variable valve timing and enhance low-speed pulling power.

The internal upgrades include high-performance pistons, which are manufactured using the same methods as those employed to create Cosworth's Formula 1 pistons. The carbon build up is reduced, also the friction is minimized, so does the weight. A perfect formula for high performance.

Forged connecting rods are made from high-strength 4340 (EN24) steel and the engine bearings boast a unique combination of design, metallurgy and engineering. Another feature are the heavy duty cylinder head studs, high-performance multi layered head gaskets and a higher-pressure oil pump, which are all installed to the engine to gain maximum performance.

As you may suggest the result is staggering. There is a huge increase in torque higher up in the rev range and improved in-gear acceleration. Now Impreza is better for everyday use as well as time-attack on race track. Larger Turbocharger and Sports Exhaust System

Turbocharging system from Cosworth features a new compressor design and wastegate actuator to supply up-rated boost pressure and deliver increased power.

The exhaust system was developed specially to allow the engine to breathe easily. It has larger capacity tubular manifolds and increased diameter downpipes speed up the flow of hot gases. The first catalyst in a non-restrictive design and larger tail pipes give the exhaust a unique sound.

After all upgrades, it is turn to make an ECU re-map and the result is amazing – CS400 generates 400ps at 5750 rpm and 542 Nm of torque.

Manual Gearbox and AWD

There is no doubt that such powerful car need full-time AWD to maintain the traction. The power is put on the road through six-speed manual transmission, which has carbon synchromesh applied to the top three ratios and a short throw linkage for quicker shifting. The clutch system is also revised by a new pressure plate, bearing and disc. The final drive ratios of the gearbox are unchanged, so the car is usable for everyday driving.

The Cosworth Impreza's full-time AWD includes front and rear limited-slip differentials, and the torque is splitted 50/50 front to rear. However, it is varied electronically according to changing conditions.  The multi-mode Driver Control centre differential with viscous coupling senses which axle has the better grip and varies the split ratio in milliseconds to distribute torque accordingly, thus maximising traction and minimising the possibility of wheelspin.

Revised Suspension

In order to improve the Cosworth Impreza's handling, steering feel and driver feedback – without compromising ride comfort, the CS400 received fine-tuned suspension.

All main suspension components are original. Cosworth collaborated with Bilstein and Eibach engineers to get perfectly balanced package, which is ideal for the new model's increased performance. The package includes Eibach coil springs and new Bilstein inserts. The car is lowered with 10mm at the front.

The main target is achieved. There is less pitch and roll when turning into corners, so keen drivers can get back on the power earlier and make the most of the car's Symmetrical All-Wheel-Drive system.

Racing Brakes Kit

The new Brakes Kit comes from AP Racing and includes 355mm ventilated front discs and

To match the new Impreza Cosworth's supercar pace, Cosworth commissioned AP Racing to develop more powerful front brakes.  Larger diameter (355 mm) ventilated front discs were motorsport-style six-pot callipers with bespoke pistons operating on larger brake pads. The fading is minised, so the car can be driven long time at race track without any concerns. The rear brakes are the original from Impreza WRX STI and the ABS system is also retained.

Pro Race Wheels with Performance Tyres

The new "Pro Race" rims have the same dimensions as the originals of the regular Impreza WRX STI model – 8.5Jx18", but they are lighter and stronger. Finished in anthracite the latest wheels from the Team Dynamics range were selected as compatible with the Subaru's five-stud design. The offset is 43mm, so the track of the car is extended with 12mm, which provides better look and improved handling. The new rims are fitted with low profile high-performance Michelin SP3 tires - 245/40 R18.

Exterior Modifications

CS400 features Xenon headlamps as standard. Because the whole car is lowered and has wider track than the original, it looks more aggressive. The aerodynamics kit includes a new shape front bumper, new fog lights, upper and lower mesh grilles and a new rear spoiler.

Discreet Cosworth badging is put on the lower grille, front seats, brake callipers and floor mats.  Individually numbered plaques are fitted on the engine and door sills. Each Cosworth Impreza STI CS400 is supplied with a numbered certificate of authenticity.

Interior Modifications and Premium Equipment

Inside the car is equipped with Recaro front seats, the rear seats and steering wheel are all re-trimmed in Cosworth-branded black leather.

Standard equipment of Cosworth Impreza CS400 features: LED (light-emitting diode) tail lamps, front and rear electric windows, 10-speaker, six-disc radio/CD player, satellite navigation, Smart-entry and push-button start, plus front, side and curtain airbags.

Warranty and Benefits

STI CS400 comes with three-year or 36,000-mile warranty, plus 12-year anti-corrosion cover and three-year paintwork warranty. You gain also three years' membership of Subaru Assistance.


Subaru Cosworth Impreza STI CS400

Body and Chassis

Five-door, five-seat hatchback, with all-steel unitary construction body shell.  Longitudinally-mounted petrol boxer engines driving the front and rear wheels (AWD) via a six-speed manual transmission.


STI 2.5-litre / 400 PS
Name Subaru Boxer
Type DOHC, horizontally opposed ‘flat four'
Capacity 2.5-litres, 2457 cc
Bore & Stroke 99.5 x 79.0 mm
Compression ratio 8.2:1
Max power 400 PS (295 kW) @ 5,750 rpm
Max torque 542 Nm (400 lb.ft) @ 3,950 rpm
Valves 16 (4-per-cylinder) with Dual AVCS
Fuel system Multi-point injection
Construction Aluminium cylinder block and heads
Emissions class Euro Stage 5

Manual Six-speed

Gear Ratios
1 3.636:1
2 2.235:1
3 1.590:1
4 1.137:1
5 0.891:1
6 0.707:1
Reverse 3.545:1
Final Drive (rear) 3.900:1


Full-time all-wheel drive with centre differential and viscous coupling, plus Vehicle Dynamics Control, Rear limited-slip differential, Front limited-slip differential and Si-Drive adjustable centre differential

Suspension & Damping
Front Fully independent subframe-mounted MacPherson Struts, with Eibach coil springs and gas-filled Bilstein shock absorbers. Anti-roll stabiliser bar
Rear Fully independent subframe-mounted Multi-Link, Eibach coil springs and Bilstein gas-filled shock absorbers (adjustable) anti-roll bar

Type Electric power-assisted rack & pinion
Gearing 2.5 turns lock-to-lock
Turning circle (m) 11.0

Front 355 x 32 mm ventilated discs with 6-pot callipers
Rear 316 x 20 mm vented discs with single-pot callipers
ABS Four-Channel anti-lock system with EBD

Wheels & Tyres
Alloy 18 x 8.5 inch, with 245 / 40 R18 directional tyres

Dimensions (mm)
Overall length 4,415
Overall width 1,795*
Overall height 1,475
Wheelbase 2,625
Front track 1,530
Rear track 1,540
Ground clearance 140
*excluding door mirrors

Interior (all models)

Front Rear
Headroom 1,024 951
Legroom 1,091 960
Shoulder room 1,430 1,426
Hip room 1,384 1,370

Capacities (all models)

Fuel tank 60 litres
Luggage (VDA) 301 litres rear seats up

1,216 litres rear seats down

Weights (kg)

Curb weight (min.) 1,505
Gross weight 1,980


Top speed / mph 155 (electronically limited
0-to-62 mph / sec 3.7

Fuel Economy (mpg)

Combined cycle [tbc]
CO2 g/km [tbc]