So, if you're shy and retiring the STi probably isn't the car for you. The same is true if you don't like getting involved in long conversations with complete strangers over the virtues of a MY03 STi PPP when compared with a P1 or an STi V5 - did I mention that you have to learn fluent Impreza, a language that makes Russian look like child's play? But if all this seems like your idea of hell, don't give up on the Subaru just yet. There's a reason for all the attention and the worryingly vehement following - and it's simply this: Subaru has been making arguably the best affordable and practical drivers' cars for nearly a decade, and has helped thousands of people to experience the sort of performance that previously wasn't available for less than ΂£30K.

This in itself makes the STi an appealing proposition, the latest model in a noble tradition of putting the frighteners on Porsche and Ferrari drivers. But it's also the STi's biggest problem. Such is the quality of the bloodline that it has to deliver consistently class-defining dynamics just to be deemed a worthy member of the Impreza progeny. Worryingly, the bug-eyed Impreza ('00-'02) seemed to have lost the finely judged chassis balance of previous models so our time with the improved '03 STi was primarily to find out if the Impreza had pulled itself together and recaptured the glory days.

Early signs were good. After the 1000-mile service (΂£48) the Impreza and I enjoyed a cold snap that fed the boxer engine with dense air and gave me a fantastic introduction to the huge rush of power that comes on stream just below 4000rpm. A non-Prodrive Performance Pack equipped STi delivers higher up the rev range but is nowhere near as fierce, nor is it as tractable before the turbo is up to speed. At ΂£1995 we'd highly recommend ticking the PPP option as it makes the car feel complete and begins to justify its chassis settings.

We found our previous non-PPP'd STi tricky to drive smoothly simply because of its all-or-nothing delivery - it promoted heavy understeer followed by a rapid flick into oversteer when the turbo woke up. BG52 was more predictable, still displaying a keenness to flick from under- to oversteer but the transition was less brutal. After failing miserably to set pulses racing at our annual Trackday Car of the Year contest (blame excessive understeer) we hoped to improve the on-road balance further with a set of 18in Prodrive alloys shod with Pirelli P Zero Neros.

As the Impreza rolled back into the car park with its titanium seven-spoke alloys I didn't give a damn about balance and ride quality - I knew I'd made the right decision. Aesthetically the classy alloys made a compelling case for themselves - I've never been a fan of gold alloys - and went some way towards justifying the ΂£1800 expense. Fortunately, the larger rims did little to harm the ride (not an STi strong point anyway) and further tamed the handling. It still demanded respect on a wet day but improvements in steering response and front end grip made the Impreza a much more fluid companion. Some additional tyre roar was the only downside.

The 10,000-mile service was carried out by Westaway Motors near Northampton and cost a very reasonable ΂£151.45. It almost goes without saying that nothing went wrong with BG52 during our tenure.

But a few doubts remain over the UK-spec STi's ability to entertain to the same degree as one of the old-school Imprezas like the P1 or the RB5 Prodrive. Barker never warmed to its spiky power delivery, its sticky gearbox or its reluctance to commit to corners without that ever-present understeer, and others shared his misgivings.

Another car also showed up the STi's deficiencies, and it wasn't arch rival Mitsubishi's Evo VIII (though the Evo has a sharpness the Impreza can't match). Instead it was another Subaru, the Japanese market-only STi Type RA Spec C (a name to impress even the most hardened Impreza aficionado) that brought sharply into focus what we really want from our Imprezas.

Sharper, faster, lighter and more focused, it's the true successor to the heroic P1 and a foil for all but the most expensive of supercars. Our STi PPP was fantastic to live with and does a convincing job of being all things to all men, but in so doing loses some of the magic that created the Impreza legend in the first place.