Road legal it might be, but really you would have an SR3 SL only if you planned some regular track outings

It's legal to drive the Radical SR3 on British roads. But should you?

Price: £69,850
Engine: 999cc, four cylinders, 16 valves, turbo-charged, 300bhp
Transmission: Six-speed sequential gearbox, rear-wheel drive
Performance: 161mph, 0-62 in 3.4sec, 28.0mpg, CO2 not quoted

Friday evening. The M25 is at a standstill, again. Most drivers have a radio to entertain them in their static state; some even have an automatic transmission so when it's time to edge forward a few feet, a simple flex of the right ankle is all that is required.

Not so for the character in the bright-yellow racing car. What is he doing here? Won't he get crushed under a foreign-registered set of wheels? I hope not, because that character is me. I am taking a radical approach to non-utilitarian motoring, driving a Radical SR3 SL.

A what? Radical Sportscars makes low-slung, ultra-light, mid-engined machines for racing and the popular sport of track days, where you and I can drive as fast as we like on tracks and hone our car-control skills in a way frowned upon on the open road.

Up to now, though, people haven't used the Peterborough-built Radicals on the road very much, because to do so has required various modifications to make them legal, if not habitable. Which brings us to the SR3 SL, whose latter initials signify Street Legal.

Being sold for use on the road means it has gained some unexpected refinements. It has, for example, a heater, interior light and electrically adjustable mirrors, and the rear spoiler is narrower, with less-savage edges. And instead of the screaming Suzuki Hayabusa motorbike engine in its race cars, this has a 300bhp version of Ford's 2.0 litre, turbocharged Ecoboost unit.

But you still have to climb over a broad fibreglass side-pod to drop into a tight bucket seat and clamp yourself in with a racing harness. And ahead of you is still a racing car's digital instrument display, and a pair of paddleshifters behind a tiny, removable steering wheel. Further ahead is a plastic windscreen, low enough not to need wipers, high enough to divert most of the air over your head. Luckily it's not raining at the moment, so forward vision is possible except when driving straight into the sun, upon which it's total light-scattered white-out.

The traffic-jammed M25 is not the place for the Radical. You need the clutch to move it away from rest, and it's both sharp and very heavy. My left foot is killing me. Thereafter you shift gears in the sequential racing gearbox without the clutch, although when driving gently, a quick dip of the pedal can smooth the mechanical clunk of engaging dog-teeth.

Set free from the motorway, the Radical is monstrously fast (0-62mph in 3.4 seconds). The engine, though loud, emits an uninteresting blare rather than an eager rasp, but there's no doubting its energy once the turbocharger is on boost.The steering is almost hyperactively darty, and on an imperfectly smooth road the Radical feels as easily distracted as a naughty puppy. Ideally, it would be calmer for a road-car role, but that's not the point. Road legal it might be, but really you would have an SR3 SL only if you planned some regular track outings.

Which is why I was on the M25, en route to Crystal Palace, where part of the old racetrack had been re-opened for a timed sprint meeting. Next day the Radical and I were poised at the start, ready for a scorch through the park. Now the steering's speed and precision made sense, as the nose scythed into the turns as though the Radical were weightless, as the power poured on to the track and the tail nibbled at the edge of grip.

Flick, flick, left, right, power, brake… what a buzz! Only the obsessive would attempt a daily commute in a Radical, but those in search of the most visceral of thrills need look no further.

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