The artic overtake is complete and, as the outside lane becomes clear, a large puff of smoke kicks out from the Escort's over-sized exhaust pipe. He's dropped it into third. He clearly means business. It is, after all, his patch - we're only just north of Essex. He nails the throttle. So do I and he fails to pull a gap. Now, if I was in a regular sports car, I'm certain he would have remained resolutely in the outside lane with his foot to the floor, but after just a couple of seconds at full bore he pulls over, eases off and watches, mouth agape, as I continue by.

The sight of a racecar on the road is about to get doubly surreal, because we're heading to Norfolk to meet up with a Radical SR3. This will be the first ever road test of two cars designed to be the ultimate trackday toys with just a nod at occasional road use. It'll be intriguing to see how they get on. Tomorrow we'll be testing them in their natural environment at Snetterton, at our final evoactive trackday of 2002, but today it's the Queen's Highway.

We've seen the Westfield before, at our Trackday Car of the Year test back in issue 046, but this Radical is different to the one at TCOTY. The 'Supersport' version we ran back then impressed all the judges, but it was marked down because it was, in effect, too good, too full-on. It was so much faster than the usual trackday suspects it threatened to be frustrating as you tripped over the slower traffic. However, the Radical SR3 range also includes this, the 'Tracksport' version, and not only does it offer more realistic trackday performance, with 165bhp rather than 252bhp, it is also considerably cheaper at ΂£31,000. That makes it a realistic alternative to a 172bhp factory-built XTR2 - this particular example cost ΂£28,500 fully built and complete with dry sump. The Radical is fitted with a Powertec-tuned 1100cc four-cylinder Kawasaki motor and power is transmitted through shafts. The Westfield has a 1300cc Suzuki Hayabusa unit and retains bike-style chain drive.

As we reach our rendezvous point, the heavens open. Obviously God has decided that if we're going to give these extreme machines a road test then we should do it properly and make it as difficult as possible. We wait for the storm to pass before moving off; the SR3's cockpit is covered by a popper-fastened tonneau, but the Westie doesn't have this 'luxury' item and, with no drain-holes in the seats or floor, it literally begins to fill with water. Time to drive the Radical then.

Dropping into the SR3 highlights further differences: the driving position is reclined, all the controls are perfectly positioned and the clutch is soft, making getaways easy. The XTR2 feels slightly awkward by comparison; both the steering wheel and the pedals are offset to the left and there's a chassis rail running beneath your heels, complicating matters further. Fit and finish are also superior in the Radical, with a carbon dash and a more organised layout; it feels more like a high-class racer, but then it does cost two and a half grand more.

We've driven some pretty exotic machinery in the past, but no Italian supercar has ever caused as much fuss as this pair. Everyone stops in their tracks and stares; kids wave, men point, women gawp and OAPs just look bemused. This has to be one of the best reasons for taking them on the road; just imagine turning up at the pub in one of these! What's more, both are unexpectedly easy to drive in town, despite the Westfield's flawed driving position.

Away from the crowds, on wet, bumpy B-roads, things are a little less fun. Track-biased tyres, low ride heights and stiff suspension unsurprisingly result in tramlining on ridges and aquaplaning over standing water. Photographer Andy Morgan, driving his Clio Cup, is easily able to pull away on these roads.

Of the two, the Westfield is the more compliant road car and, once you ignore its fidgeting over the bumps, it starts to become fun. And it's not just a novelty thing. The steering has plenty of feel and, when you do get the opportunity to squeeze the throttle, it goes as fast it looks. The acceleration is nothing short of extraordinary and the noise is... well, pure race- bike. The demonic yowl would have battered my ears into submission if it were not for the Dainese helmet clamped onto my head.

The SR3 is longer and lower, with just 40mm ground clearance (it can be raised to 100mm) and as the roads start to dry and we find some smoother sections it's clear that we could now turn the tables on the Clio. Still, you're always aware of the minimal ground clearance and flinch every time you ride a pothole. That said, the sickening graunch of glassfibre splitters kissing bitumen never materialised on our test route, and ironically it was the speed bumps on the Snetterton access roads that gave most cause for concern. Both cars passed this test too, although we had to drive diagonally across them.

Out on the track, nothing gets close to either of them; regular road cars just don't have a chance. With these cars there is an invisible energy at work: downforce is an extraordinary thing to experience, and through the high-speed stuff these cars generate freakish levels of grip. The SR3 ekes out a distinct advantage here - it is the more aerodynamically efficient of the two, the more stable and the more accurate. Everything happens staggeringly quickly; by the time you've thought about an approaching corner, you're already through it, and your confidence grows equally rapidly. Cornering speeds are lower in the XTR2, but still very high in real terms. With the Westfield's extra straight-line speed, lap times would be similar, but we feel the Radical would still just edge it.

Are they too fast for trackdays? No, but you have to drive within other people's limits - even an average driver will be mixing it with track- prepared Porsches. So which would we choose? Both are too extreme for regular road use, though both are entertaining enough for the occasional blast or the drive to the racetrack. The Westie is marginally ahead on the road; the Radical the more satisfying track car. As road mileage is likely to be minimal, it ultimately boils down to their circuit performance. We'd take the SR3.