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When we first drove the Radical RXC it wasn’t difficult to spot its weakness.

So superb was its chassis balance and so eye-popping the level of downforce available from that Le Mans-style bodywork, it was clear before the tyres were warm that the car could handle more than its current 350bhp. A lot more. This, the new Radical RXC500, is the answer.

You’d think the clue was in the title, but in fact the new car has 530bhp, courtesy of a new 3.5-litre Ford Ecoboost motor breathing through a pair of water-cooled Garrett GT28 turbochargers.

Although the all aluminium engine is a stock Ford part – indeed you can buy one for your F150 Pick Up - Radical has developed the plenum intake to incorporate 12 fuel injectors instead of the usual six.

Radical has also come up with its own twin-phase wastegate actuators for more precise boost management and heat shields to contain the additional heat of the engine.

The rest of the car is as before, with a carbon-steel spaceframe chassis clad in composite bodywork which, with the carbonfibre rear wing, generates 900kg of downforce at 185mph.

The pushrod suspension is by double wishbones all round, while braking comes courtesy of four chunky fully floating discs clamped by six-piston calipers. Radical’s primary goal for the car is to use it to extend the company's 10-year reign as holders of the Nürburgring lap record for a road car.

Radical first broke the record in 2005 with an SR8 LM driven by Michael Vergers, who went on to set the existing record of 6min 48sec in the same car in 2009. The attempt will take place in August with an as yet unnamed driver at the wheel.

In the context of a purpose-built racing car, the RXC500 is a quick, complete, very forgiving and effective weapon. It's the additional torque as much as the power of the new turbo engine that now makes it possible to realise almost the full potential of the chassis, although it leaves just the suggestion it could handle up to 600bhp.

The flat-shift paddle-actuated gearbox is ideal under full load, and the combination of downforce and the chassis’ inherent stability means you can trail brake the car all the way into an apex.

In the context of a car with air conditioning and a comfortable cabin, that’s fully Type Approved and wears number plates, it is something close to a miracle.

What the new engine really provides, beyond a 0-100mph time of 6.8sec, is the ability to really bring the rest of the car to life. Whereas the normally aspirated RXC would get you into a corner at vast speed, from the apex onward it felt, well, a bit limp. Unable to challenge the traction of the rear tyres or to build speed in order to really maximise the vast aero resources the body placed at your disposal, it felt like its claws had been clipped.

No longer. With turbo power it gathers speed relentlessly, showing over 160mph on Silverstone’s Hangar straight despite the drag of the rear wing, before flinging you into Stowe with world-class electric power steering, a couple of snatched downshifts and one sharp stab on a braking system that benefits as much from the downforce as its cornering ability does.

And then you pile the power on again, forcing the car to the absolute limit where, in this very early prototype phase, it understeers just a little too much, but nothing a little set-up work won’t swiftly eradicate.

Better still, the way the turbos pick up the power from low revs is remarkable, as is the throttle response throughout the powerband. The engine both sounds and feels turbocharged, but Radical has done such a fine job of mapping the throttle response and torque curve that you never find yourself in the wrong gear nor waiting for the power to arrive. It’s there, and by the bucketload - all the time.

On the downside, the engine’s sound is relatively bland, its rev range is limited to little more than 6000rpm and the Quaife sequential gearbox is very clunky if driven gently. You could negotiate town centres if you had to, but that and the limited rearward visibility would be enough to deter most people most of the time.

There is no doubt that £143,500 is a lot of money and that an Ariel Atom 3.5R, with all the right bits on it, is still probably £60,000 cheaper and, in a straight line at least, a little quicker. But with the RXC500 you’re buying not only the all-weather practicality the Atom lacks, but an on-track ability you’ll find in no other car of a similar price.

If it does lap the Nürburgring in under 6min 48sec this summer, it will beat not just Radical’s own record but the time set by the Porsche 918 Spyder, too.

And Radical plans to drive the car there and back. On that basis, £143,500 looks positively cheap.

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