certainly taken a radical new direction: it's only available as a five-door hatchback, the base versions of which have been criticised for their insipid looks. STI version is the utter opposite of the dull Impreza hatch, with its wide wheelarches, aggressive spoilers and multiple vents. While the essentials remain the same - turbocharged four-cylinder 
'boxer' engine, permanent four-wheel drive, close-ratio six-speed gearbox - there are more driver aids - including stability control for the first time - and more power. When it goes on sale in March 2008, it's going to have to beat the Mitsubishi Evo X due at the same time while Subaru also says it's raising its game to tempt Audi and BMW buyers.
'boxer' engine, permanent four-wheel drive, close-ratio six-speed gearbox - there are more driver aids - including stability control for the first time - and more power. When it goes on sale in March 2008, it's going to have to beat the Mitsubishi Evo X due at the same time while Subaru also says it's raising its game to tempt Audi and BMW buyers.Our Fuji Speedway drive in Japan centred around the Japanese-spec STI, which sticks with a 2.0-litre engine with 304bhp; we will be getting a 2.5-litre 296bhp engine in the UK. There's no doubting the raw power of the turbocharged flat-four powerplant, at least once its turbo is spinning above 3000rpm or so. The STI remains one of the quickest-accelerating cars this side of a supercar,
with an estimated 0-62mph time of 4.8 seconds. However, the 2.0-litre engine suffers from a lack of low-down torque; we hope and expect that the 2.5-litre engine will have better response at lower revs.
with an estimated 0-62mph time of 4.8 seconds. However, the 2.0-litre engine suffers from a lack of low-down torque; we hope and expect that the 2.5-litre engine will have better response at lower revs.A new feature for the STI is Subaru's Si-Drive - a dial that lets you switch between engine response programs. Comprising normal, sharp and super sharp, the settings progressively speed up throttle reaction times to suit your mood and driving style. The six-speed gearbox is basically the same as before but its shift action is faster and lighter; a good thing, as the old STI gearbox's mechanical feel wasn't very appealing. When it comes to stopping, the 
Brembo brakes certainly don't lack power. But we were disappointed to feel just how unsettled the STI can become during hard braking on the Fuji circuit.Watch our video roadtest of the Subaru Impreza STI
Brembo brakes certainly don't lack power. But we were disappointed to feel just how unsettled the STI can become during hard braking on the Fuji circuit.Watch our video roadtest of the Subaru Impreza STIImprezas are all about grip, and four-wheel drive remains a major contributor to the STI's uncanny levels of purchase on the tarmac. The tyres will eventually start squealing in protest, but only at very high cornering speeds. As before, the STI allows you to dial in how the torque is directed to the front and rear axles via a Driver's Control Centre Differential which now incorporates a switchable auto mode for the first time. Pulling the control switch all the way back does noticeably reduce understeer but the tendency for Impreza's nose to push wide around corners remains an annoying feature.
For the first time ever for an Impreza, the STI incorporates a stability control system. Heresy? Not really. It boosts safety in extremis and you can still switch if off, or even to a half-way
'Traction' mode that delays its onset to increase driver feel. The steering is rather lighter than many performance cars but you always feel utterly confident that the STI will get you around bends. And there's a surprising amount of body roll for such a performance-orientated car, the result of some soft suspension settings that improve the ride quality over the previous STI. Overall noise is also a good deal more subdued now.
For the first time ever for an Impreza, the STI incorporates a stability control system. Heresy? Not really. It boosts safety in extremis and you can still switch if off, or even to a half-way
'Traction' mode that delays its onset to increase driver feel. The steering is rather lighter than many performance cars but you always feel utterly confident that the STI will get you around bends. And there's a surprising amount of body roll for such a performance-orientated car, the result of some soft suspension settings that improve the ride quality over the previous STI. Overall noise is also a good deal more subdued now.Oh dear. For a car that Subaru says it wants to compete on quality with Audi and BMW, the cabin feels like a car that costs half its price, not surprising with the regular Impreza starting at £12,495. There are swathes of hard, low-rent plastic in the cabin, which is a shame as the instruments and overall design are quite attractive. The five-door layout boosts practicality and there is a decent sized boot, complete with folding seats for the first time. The longer wheelbase of the new Impreza, and the wider body, make room inside much better. Two types of front seat are on offer: standard leather-and-Alcantara seats or optional deeply bucketed and very supportive Recaro items.
Economy and safety
You don't buy an Impreza STI if you're worried about fuel consumption as it's always been terrible. While there are no official figures yet, Subaru claims that the new STI will be
fractionally more frugal than the last one but that was certainly no miser at 25.9mpg. As for safety, the four-wheel drive system certainly offers excellent grip, and finally the STI moves into the modern age with curtain airbags and stability control for the first time.The MSN Cars verdict: 4/5
First, the good news: the all-new STI remains a titanically fast performance car with astonishing grip. Its design is also just aggressive enough to please existing enthusiasts, without being too over-the-top. And it's a good deal more practical, more refined and rides better. But the new STI doesn't represent the great leap forward we had hoped for. Despite all the driver aids, the STI remains a stubborn understeerer, while its straight-line braking is rather wayward. Regular performance hatches may not be as quick, but they've caught up with Subaru in terms of the fun factor. We'll have to wait and see if the larger-engined UK version, due in March 2008, can iron out the problems.
Ratings out of five: Subaru Impreza WRX STI
Performance
*****
Ride & handling
****
Interior
***
Safety
****
Price
****
Practicality
****
Fuel economy
**
MSN Cars verdict
****
Need to know
Petrol engines: 2.5-litre turbocharged
Power (bhp) : 296
Torque (lb/ft): 300
0-62 (secs) : 4.0 (est)
Top speed (mph) :160 (est)
Combined mpg: n/a
CO2/tax: n/a
