STANDARD Impreza STI not fast enough for you? Then Subaru UK has a new model that could be just your cup of Castrol.

It has taken a standard STI and handed it over to Prodrive - the company that masterminded the Subaru world rally effort for more than a decade.

Prodrive modifies the engine's electronic control unit and bolts on a new exhaust that exits the rear via macho quad stainless steel mufflers. Work done the STI is strapped to a dynometer to measure its power. The result? A hair raising 330 PS at 5,400 rpm compared to a "mere" 300PS at 6,000 rpm on the ordinary car.

And boy, does that make this car quick.

It's not just hot hatch quick, it's supercar-eating quick. From a standstill you'll see 60 mph in a mere 4.4 seconds. That's a full second faster than a Lamborghini Countach, the crazy-looking Italian stallion that coined the term "supercar".

There's more torque, too, and it's available lower in the rev range so the 330S should be easier to drive at sensible speeds.

If only that were true.

This car is in a very high state of tune and the engine behaves accordingly.

Around town it coughed and spluttered in traffic like a thoroughbred race horse entered in a donkey derby.

The engine's step-off (the transition from stationary to moving away) isn't great and it took a lot of concentration to pull away smoothly.

On cold mornings the engine felt dull until it was thoroughly warmed up - like cars used to feel when the driver had to juggle a manual choke and the fuelling wasn't quite right.

Mind you, all that's forgotten when you can give the car it's head.

Below 3,500 rpm it doesn't want to know but beyond that and wham... you'll swear someone just switched the afterburners on.

The STI can reach the legal limit in second gear and, were you on a race track, it wouldn't stop charging until the speedo was reading south of 150 mph.

Mind you, 3,500 rpm equates to almost 90 mph in top (sixth) gear - so you'll be using that ratio as a fuel saving over-drive in the UK.

The high gearing helps calm things down when you're cruising the motorway, but an STI is never going to give the Toyota Prius a run for its money at the pumps. Driving with economy firmly on my mind (I'm a Yorkshireman) I still couldn't coax the fuel computer above 30 mpg.

But all that is forgotten when the STi is "in the zone" as the engine, gearbox and four-wheel drive chassis conspire to produce an exhilarating driving experience the equal of supercar cars costing three times the £29,890 Subaru asks for the 330S.

Fans of Gran Turismo, the video game, will love fiddling with the Subaru Drive Control Centre Differential which alters the amount of torque apportioned to the axles, enhancing straight line stability or the car's agility through twisty forest tracks. This goes hand-in-hand with ECU re-mapping software called Si-Mode.

However much you try to mess it up, there's always an astonishing amount of grip. The flat four engine keeps the centre of gravity as low as possible for optimum mass distribution. If you want to find the limit I suggest you find a race track - it's unstickable at legal speeds on UK roads.

The only fly in the ointment is the steering which lacks the scalpel-like precision of a Mitsubishi Evo on initial turn-in.

Older Imprezas used to parade their prowess with gaudy bodykit add-ons.

The new Impreza may carry a big stick but it speaks softly. Subaru has fitted a body kit but it's a much more subtle affair - the wheel arches are flared out while the chin spoiler and rear bumper are deeper.

Interestingly, this Impreza is actually shorter than its predecessor but boasts more interior space thanks to a longer wheelbase. Multi-link rear suspension helps improve the boot space, too, and a hatchback is far more practical than the old saloon's boot.

Inside the interior feels like a different world from the old Impreza, with quality plastics, lashings of leather and fancy Alcantara fabric on the Recaro seats. The STi finally feels like a car costing £30k.

There's plenty of room in the front and, while the Recaros rob a bit of knee room in the back, rear passengers get a better deal too.

The stereo has a big, impressive sound and climate control keeps everything cool even if you lose yours.

This is a car for enthusiasts. It is not a rational purchase. Any number of far cheaper cars can do the day-to-day stuff better.

You will never stretch the STi's performance on UK roads - not without serious risk to your licence anyway - and nor should you even try.

But the STi is special. It's a car that appeals to your heart not your head and, for many enthusiasts, it represents some kind of ultimate.

It may sound silly for a car that costs so much to run and insure, but for less than £30,000 the Subaru 330S is a solid gold bargain.

* Why not join me on Twitter? From this week I'll be posting regular messages about my testing activities and other car related news. This week I'll be driving the new Megane scenic.

If you drive a Scenic why not let me know what you think? If I get some good insight I'll use it in my next review.

SPECIFICATION

Engine: 2.5-litre flat four turbocharged
Max power: 330 PS @ 5,400 rpm
Max torque: 346.6 lb/ft @ 3,400 rpm
Top speed: 155 mph
0-60 mph: 4.4 seconds
Fuel consumption: don't ask.

CO2 emissions: 243 g/km
Road tax: £405
Equipment: Electric windows, air conditioning, Alcantara Recaro sports bucket seats, leather steering wheel, CD/MP3 radio, ABS, four-wheel drive.