| Week at the Wheel | Subaru Impreza WRX STI 330S |

Inside & Out:

There are a few external clues to distinguish the 330S from regular WRX STI model. First up, the twin rear exhaust pipes are up to 90mm in bore now, which Subaru says helps free up the noise a little to give the S a distinctive burble beloved of Subaru fans. There's also a small '330S' badge on the boot, but that's the only overt sign of this car's increased power. Keen-eyed Subaru spotters will note the 18-inch alloy wheels and front splitter for better aerodynamics, but that's about it for the outside.

Move inside the 330S and you get unique Recaro sports seats in the front finished in leather. There's also standard satellite navigation, but we found the trio of digital instruments far more entertaining to watch. The driving position is comfortable and quite low-set for a hatch thanks to the Recaro seat, but the view out is unhindered in most directions. With the seat and steering wheel adjusted to suit the driver, the rest of the controls are laid out in a sensible manner. It's just a pity the Impreza's dash doesn't have a touch more flair to its styling. For rear seat passengers, there's reasonable space and the Impreza's boot is usefully large.

Engine & Transmission:

This is the heart of any Impreza and the area where the 330S has been improved and tweaked the most. The 2.5-litre 'boxer' flat-four engine remains the same size as in the standard WRX STI, but Prodrive has come up with a modified ECU for the engine to free up power so the engine now produces 325bhp at a still accessible 5,400rpm. The new exhaust also helps with the search for extra grunt and Subaru has definitely recovered the trademark warble that marks out the Impreza from any other high performance hatch. The new found power reduces the 0-62mph lunge from the standard STI's 5.2 seconds to 4.8 seconds, with top speed rising to 155mph. That keeps the 330S in the hunt with Mitsubishi's Evo X, but more significant is the extra mid-range wallop delivered by 347lb.ft of torque. This allows the Impreza to overtake at will, picking off the weak and unsuspecting like a sniper on a church tower. We'd still like a more accurate gait to the six-speed manual gearbox, but the ratios are well chosen and the 330S can even manage a passable impression of a (relatively) refined motorway cruiser.

For added traction on twistier roads and in slippery conditions, Subaru provides its SI-Drive control to vary the sensitivity of the throttle. There's also a Variable Dynamics Control, sited just behind the gear lever, which alters the amount of power divided between the front and rear axles via the centre differential. Working in conjunction with the limited slip front differential, the 330S has superb traction in all conditions, but we found ourselves leaving the SI-Drive and tricky diff stuff in automatic mode most of the time and that it works just fine like that.

Ride & Handling:

Anyone expecting a velvet smooth ride from a hot Impreza is in for a disappointment, though the 330S is not wound down as tight as you might think. Sure, it picks up on almost every bump and graze in the road, but it's not as wearing as an Evo X when all you want to do is just get where you're going. This makes a big difference to the 330S's every day usability and means you'd be less likely to leave it in the garage when a long trip beckons.

The knock-on effect of the almost reasonable ride comfort is that the 330S leans more in corners than at its arch rival from Mitsubishi. It's not a drunken loll - more a feeling of the forces building and acting on the car - whereas the Evo X seems to have made an unholy pact with the devil that allows it to go ever faster round bends with no apparent effects. Which you prefer is down to personal taste, but what we can say is the 330S gives its driver a little more warning of its considerable limits before things go too far. More feel through the steering would further help here, but the Impreza is still enormous fun to drive. Push hard and the rear will sneak out of line, but in a controllable fashion thanks to standard yaw rate sensors monitoring every situation. Overall, the 330S is harder, faster and better than the standard STI, so it's job done on that front.

Equipment, Economy & Value for Money:

Subaru has thrown the lot at the 330S: it comes with satellite navigation, clever traction-aiding centre differential and electronics, swish leather seats, climate control and decent stereo. However, it's hard to ignore that this is an Impreza that costs as much as a decently appointed BMW 3 Series Coupé, Audi TT or a large number of more eye-catching coupés. Because of the price and the competition at this level, the Impreza's cabin materials are disappointingly plain and uninteresting to look at. On the plus side, you get four-wheel drive and storming performance, and it costs about the same as its opposite number in the Mitsubishi Evo X camp. As for economy, we tried to get close to the 23.7mpg combined figure with some gentle motorway driving, but the best we could manage was 20.3mpg. Drive hard or mooch about town and this soon drops further, so you will develop a close relationship with the petrol pump of you decide a 330S is for you. Throw in steep insurance, servicing that won't come cheap and pricey consumables such as tyres and the 330S is not for the faint of finance.

Overall:

Subaru has come up with a harder core Impreza in the 330S. There's no doubting the Prodrive finesse under the bonnet and the impressive grip offered by the four-wheel drive chassis. There are faults, such as the steering that needs more sensation to keep the driver fully informed and the lacklustre cabin materials, but this car is all about the drive. It's not as raw or as demanding as a Mitsubishi Evo X is, but that can be a good thing as the 330S is easier to live with day in, day out, and you don't have to stop for fuel every five minutes as you do in the Evo. That said, the 330S will not be cheap to run and it costs more than £4,000 over the price of the standard STI. Is it worth it? Probably not, but then you can always have the engine upgrade on its own from Prodrive for a lot less cash and that is something we would recommend.