Ever since its introduction in 2001, the Subaru Impreza WRX STI has been a byword for exceptional real-world driving performance writes Sharon Walters.

The new 2011 model, on sale from this month, incorporates a wide range of developments which maintain the continual evolution of this iconic vehicle.

So synonymous are the six letters ‘WRX STI’ with automotive exhilaration, that for this latest 2011 generation, the ‘Impreza’ moniker has been dropped and the new car will henceforth be known simply as the ‘Subaru WRX STI’.

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In response to significant market demand the four-door saloon version of the Subaru WRX STI is once again available, after an absence of three years.

The hatchback variant will sit alongside the saloon, and this will consequently mark the first time that four- and five-door versions of the car have been sold together in the UK.

In order to further refine its all-round performance, the 2011 WRX STI has been extensively tested under a wide variety of weather, traffic and road conditions, ranging from slow, congested city driving and rapid B-road sprints, to extreme ‘hot laps’ around famous racing circuits – including the notorious Nordschleife at the Nürburgring in Germany.

The new WRX STI benefits from a stiffened bodyshell and an extensively reworked suspension system – based upon the marque’s widely praised ‘spec. C’ set-up.

Lower ride height and wider tyres also contribute to more direct and accurate control of the car and greater feedback for the driver.

The more rigid bodyshell has also made it possible to increase suspension travel, benefiting road-holding as well as ride refinement.

An all-new design of wheel saves approximately two kilograms of un-sprung weight per corner compared to the outgoing model, helping to further improve ride and handling, as well as enhancing the car’s appearance.

Exterior styling is extensively revised, with new bumpers, enlarged rear quarter panels and lower ride height giving the car a more muscular presence.

Inside, the quality of the cabin materials has been upgraded, and the driver and passenger are assured of a secure and comfortable seating position thanks to the introduction of all-new Recaro bucket seats.

The widely praised 2.5-litre Subaru boxer 16-valve turbo engine with Dual Active Valve Control produces 300ps at 6,000rpm and massive torque – with a peak of 407Nm at 4,000rpm – even from low-revs.

While these outputs are unchanged from the outgoing STI, improved torque delivery throughout the rev range translates into better response and more linear acceleration.

The zero-to-62mph sprint is achieved in just 5.2 seconds.

Significantly, the revised engine is cleaner, and successfully meets Euro 5 exhaust emissions standards.

Central to the agile handling of Subaru vehicles is the company’s legendary Symmetrical AWD (all-wheel drive) system.

This consists of the horizontally-opposed boxer engine, with its intrinsic low centre of gravity, combined with advanced AWD technology incorporating sophisticated front, centre and rear differentials.

For the new WRX STI the system has been uprated, with revised settings for the differentials.

The car features a default setting of 41 / 59 per cent front / rear torque distribution for optimum balance, and the driver can adjust this while on the move using the four-mode (Driver’s Control Centre Differential) system.

The WRX STI also incorporates Multi-Mode VDC (Vehicle Dynamics Control) – Subaru’s advanced electronic stability control (ESC), allowing the driver to modify the point of intervention of this electronic driver aid to suit their own tastes or driving conditions.

In order to develop a vehicle that provides exceptional levels of high performance and precision handling, together with user-friendly daily motoring driveability on demand, Subaru has further tuned its three-mode SI-Drive (Subaru Intelligent Drive) system, which can be used to adjust the engine’s characteristics to best suit a variety of driving conditions.

Aficionados of Subaru performance vehicles will be cheered by the news that a new exhaust system, with a larger centre muffler and larger diameter piping, enhances the engine’s iconic boxer ‘burble’.

The WRX STI is now available, priced at £32,995 on-the-road for both the four-and five-door variants.

Standard equipment includes keyless entry, push-button start, front log lamps, hill start assist, climate control air-conditioning, remote central locking, electric windows front and rear, an all-new radio-CD unit with a 10-speaker audio system, AUX and USB input jacks, hands-free Bluetooth system and cruise control.