Subaru's Impreza WRX STi WR1, which was first unveiled at this year's Autosport show as a very public way of celebrating Petter Solberg's 2003 WRC victory, is about to hit the road in production form. And it's going to be the fastest Scooby yet, with 315bhp at 5800rpm and 310lb ft at 4000rpm giving it a 0-62 mph time of - get ready - 4.25 seconds.

The extra output - which, as with the STi upon which the WR1 is based, comes courtesy of Subaru's clever friends at Prodrive - was liberated by revising the engine's ECU and treating the exhaust to a high-flow catalyst and sports silencer. The result is a vehicle that'll outperform any other road-going Impreza in official UK spec - yes, even the STi with the optional Prodrive Performance Pack, itself not exactly a slouch.

But of course, it's not just about straight-line speed. This is one of the fastest ever point-to-pointers, after all, and mere supercar performance wouldn't mean much if it didn't at least match the almost absurd cornering ability of previous hot Imprezas. You'll be pleased to hear, then, that a 25mm lower ride height, with uprated springs and bump-stops, is just the beginning.

What really sets the WR1 apart as a rally-derived machine is its DCCD. You know, DCCD. This stands for Driver's Control Centre Differential, and is basically a switch next to the handbrake with which you can tune the vehicle's permanent four-wheel drive system by controlling the torque split between the front and rear wheels. If you want sharper turn-in, for example, or more stable straight-line running (or crazy tail-happy show-off potential), this little box of tricks is your passport to feeling more like a pro than ever.

You'll look like it, too, thanks to the WR1's unique metallic blue paintwork and 18-inch alloys, the latter shod with 225/45R18 Pirelli P Zeros, as well as its new driving lamps and stainless steel mesh grille. On the inside, your status is confirmed by anthracite suede-effect seats, a special gear ****, imaged carpet mats (whatever that means) and a tax disc holder engraved with your vehicle's special edition number.

Special edition? Yes, they're only making 500 of these ultimate Imprezas available, so don't hang about. With a dealer price of £29,995 making this quite possibly the fastest-for-your-money car on the market, indeed, hanging about is not an option. Alan Kidd