WRX STi

January sees the launch of the 260bhp (253 lb-ft of torque) Impreza WRX STi. Two versions will be available in the UK – the ‘standard’ STi and the special edition STi Prodrive Style with Prodrive-designed spoilers, grille and front bumper.

Both will be designated and badged ‘Type-UK’ as Suburu seek to distinguish them from grey imports which. Subaru are keen to differentiate them from ‘grey’ imports which do not have European Type Approval and they are providing extra features to differentiate them too.

Amongst the additional features included for the UK are the security features necessary to discourage scrotes from making off with the new toys. These include a Category One alarm/immobiliser and a satellite tracking system. Type UK cars also get enhanced rust proofing locking wheel nuts and a three year/60,000 mile warranty plus three year membership of Subaru Assistance.

WRX STi styling features include smoked glass projector beam headlamps, bigger bonnet air intakes and a single large-diameter rear exhaust pipe. Other shared differences to the regular WRX include special gold-coloured spoked alloy wheels, colour-keyed sill spoilers and an interior featuring blue suede-effect seats with STi logos and red stitching for the steering wheel, gear knob and handbrake lever.

In addition, the STi Prodrive Style features a massive high-riding boot spoiler, newly designed sill spoilers and a deeper, squarer front bumper. The grille and badging resemble the WRC rally car. Interior enhancements over the standard STi include dark blue-coloured instruments with red needles. Also inside - and sure to please gadget freaks - is the switch to spray the intercooler with water.

The Impreza STi will be available in four colours: WR Blue Mica, Blue Black Mica, Premium Silver Metallic and Pure White, the latter two being special order only. Provide Style customers can choose between WR Blue Mica and Blue Black Mica. The Prodrive Style costs £27,495 on-the-road.

Performance? 148mph and 0-60 in 5.2 seconds.

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ENGINE

Up to 80 per cent of the STi’s all-alloy engine is new compared to the standard turbocharged 2.0 litre four-cam ‘boxer’ unit as fitted to the regular Impreza WRX. In order to meet the stringent Euro3 exhaust emission levels, the catalyst is uprated, the air-fuel ratio sensor modified and special multi-hole fuel-injectors fitted. Engine strength and rigidity are boosted by using semi-closed-deck cylinder blocks, reshaping the piston head, fitting screw-in type connecting rods and using forged pistons and shimless valve lifters. Also aimed at high-rev durability are sodium-filled exhaust valves and hollow intake valves. A larger intercooler and air intake provide better cooling and a special intercooler water spray is fitted, operated by the driver with the water tank fitted in the boot. Also specially fitted to the STi is Subaru’s Active Valve Control System – variable valve timing – which ensures maximum engine response over a wide rev-range. The result is a maximum power output of 265 PS (261.5 bhp/195 kW) at an accessible 6,000 rpm and 253 lb ft (343 Nm) torque at an equally usable 4,000 rpm. This compares with the standard WRX figures of 218 PS at 5,600 rpm and 215.4 lb ft of torque at 3,600 rpm – significant increases of 47 PS and 37.6 lb ft. As with the normal WRX, the horizontally-opposed four-cam, 16-valve ‘boxer’ engine has a bore and stroke of 92x75 mm for a capacity of 1,994 cc and runs on an 8.0:1 compression ratio. While not a top priority for performance car owners, fuel economy is a respectable 29.7 mpg on the Extra Urban cycle.

TRANSMISSION

The European version of the STi features the same completely new six-speed transmission as the Japanese model. This short-throw close-ratio ‘box’ has been designed to withstand high torque outputs and features extra rigidity thanks to expanding the distance of the main gear shaft by 10 mm and increasing the facewidth of the gears. Instead of turning the STi’s sixth gear into an economy-orientated overdrive, Subaru’s engineers have chosen low gearing for lively acceleration. For example, the STi’s fourth gear virtually matches third on the standard WRX, while sixth pulls 24.5 mph/1000 rpm versus the WRX’s 24.7/1000 rpm. The clutch is uprated and larger, with increased loading on the clutch cover. Meanwhile, both lubrication and cooling are improved through the use of an oil pump in the main case. Engagement of reverse gear now requires the lifting of a pull-up slider ring.

WHEELS / TYRES / BRAKES

The STi’s wheels and tyres are slightly larger than the standard WRX. The specially designed multi-spoke gold alloy wheels measure 17x7.5 ins instead of 17x7 ins and the tyres grow from 215/45 to 225/45. Brakes are supplied by Brembo and include an ABS system. Key features include larger ventilated front and rear brakes with four-pot aluminium callipers at the front and twin-pot offset opposed aluminium callipers at the rear. Actual front/rear brake size grows from the 11.5 ins (292mm)/11.3 ins (288mm) of the standard WRX to 13 ins (330mm)/12 ins (305mm) for the STi. The enhanced ABS system also benefits from a lateral G sensor and EBD (Electronic Brake Distribution). This ensures maximum braking control.