Front-wheel drive and 328bhp. This does not compute. Was it Saab that once said 250bhp was the limit for a front-drive road car? That was a while ago though, so maybe science has moved on.

Yes, I know all those arguments about how front-wheel drive corrupts the steering and the purity of the driving experience. But to see if a front-wheel-drive car can function with 328bhp, if it is actually able to move in a purely forward direction should the road turn damp and not fling itself head-first into a hedge, would still be an interesting exercise. Pointless, of course (we know the answer, don't we?) but interesting.

Then you drive the Alfa 147 GTA as envisaged by Autodelta and you discover that the impossible is not. It works. Not only does it get its power down, it does so with rather more decorum than a Ford Focus RS.

Here we are on a sweeping switchback in Northumberland's Cheviot Hills. The road is damp, but right now also empty for a couple of miles ahead; ideal territory to put this Alfa to the test. Slow down, into second gear and plant your right foot to the floor. There is much amazement here: at the traction from the 225/40 R18 Michelin Pilot Sports, at the deluge of torque on instant tap and, most noticeably, the sound; it's a kind of old-911-plus-Alfa-rasp, crackling fizz over a beaty bass backdrop, howling heroically as the 7300rpm peak power speed approaches.

I'm being squashed back in my seat, the acceleration impressive not so much for its ferocity as for its unrelenting continuity. The V6 has been bored out to 101mm, as far as it can go without collapsing in a pile of aluminium pieces with all cylinders joined up, which makes it very oversquare (hence the revviness). It also makes it a 3.7-litre engine. Think about that: 3.7 litres, 328bhp, in a front-wheel drive hatchback. A first, I think.

On the Alfa hurtles, an Alfa 147 apparently quicker than an M3. Then I slow; still in sixth gear, quite long-striding at 25mph per 1000rpm, meaning I can squirt past a tractor at 50mph with just an ankle-flex. Torque like this is delicious, especially when delivered with such an instant throttle response (remapping and a larger, Ferrari-sourced throttle body help here).

But now there are bends, downhill bends. Uprated front brakes, using six-pot AP Racing Galfer callipers and 355mm diameter dimpled discs (not shown in the above pic), bite with race-car-like precision and insistence. Then I turn: the suspension is lower and stiffer, and there's more weight transfer at the back. Together they banish the slightly nose-heavy, disconnected feel we've criticised on the standard GTA. It's much pointier and more precise now, with a quick, linear steering response and some meaningful feedback.

But what happens if I unleash that torque in the turn? There's a brief lunge outwards, then the diff hauls the nose back in and holds it on course. What it does not do is to pull the nose so far in that you have to unwind the steering, as on a Focus RS. It just pulls the Alfa through the bend, getting the power down tidily enough to barely trigger the traction control.

Sounds good so far, yes? Here could be the ultimate in engaging modern Alfas, but there's a heavy price to pay. The ride, fidgety on smooth roads and endlessly ker-plunk on a concrete motorway, is almost comically bad on the lumpy surfaces that make up many of our ultimate driving roads. The suspension fidgets and thuds and jitters and checks as though the rear springs belong to an unladen Iveco minibus; your passengers will hate you.

You could tire of the low-rpm engine boom after a while, too, and the clutch-type slippy diff clanks and grates when turning tightly on a trailing throttle as if the driveshafts are about to give up.

The diff I can accept, because it otherwise works so well. The boom can be fixed with a different centre silencer, so you can keep the four tailpipes. But the suspension must be fixed for this to be a credible car, and Autodelta's Jano Djelalian, who built this machine to suit the tastes of a young and rich customer, is confident he can do it. The trick will be to do it without spoiling the balance and the sharpness.

How rich? Autodelta reckons on ΂£39,234 to replicate this GTA (complete with wheels, bodykit and the bonnet with its giant dummy exit-vents), which defies normal logic. But such logic doesn't apply here. I'll give it five stars for the engine, four for the handling (the turning circle is atrocious), and one for the ride. For now, we'll settle for three. After all, it does redefine the possible.