Depending on the context, the word ‘tolerance’ has multiple definitions. In engineering terms, it’s an allowable variance from a specified quantity – tight enough to have no effect on performance. In human terms, it’s the capacity to endure continued subjection to adverse conditions, or thought, without reaction.

We all have different levels of tolerance, be it physical or emotional. So, too, do car manufacturers – based upon brand values, target markets, fiscal responsibilities and global legislation. This leads to inevitable compromises - no car is perfect, some just get closer to perfection than others. Occasionally, however, a manufacturer chooses to tighten all tolerances in one specific direction - the pursuit of driving pleasure and performance - and to hell with the consequences. With every tweak comes a subtle shift in the equilibrium towards the more focused and extreme experience, but how far should the boundaries be pushed before the balance reaches a tipping point where the added driver appeal breaks the roadworthy sensibility?

The Renaultsport Megane R26.R is a good candidate for a case study. For many, basing a stripped-out track warrior on a humdrum family hatchback seems like an inevitable recipe for a flawed and compromised machine. For a select few, however, it’s a rolling advertisement for what can be done when talented people are truly let off the leash.

When launched in 2009, the R26.R moved the goalposts for an already title-contending hot hatch so far over to the extreme end of the spectrum that it started appearing in comparison tests with dedicated, ground-up sports cars from the likes of Lotus and Caterham. Motoring publications tripped over themselves to praise it and started to mention its handling dexterity in the same sentence as the DC2 Integra Type-R… Some journalists even went as far as saying it was superior.

A hardcore diet of 123kg, revised spring rates and dampers, plus super sticky, semi-slick Toyo R888 tyres, gave the Megane a lick of speed no 227bhp car had any right to possess down a twisting road or racetrack. A scorching Nürburgring lap record of just 8:17 underlined the car's pace and ability. Yet many cars languished in showrooms unsold – the buying public unconvinced by something so extreme with ‘wrong-wheel drive’, silly stickers and a basic list price of £23,815. Perhaps they didn't understand – or have the stomach for – the six-point harnesses, plexiglass rear and side windows, deleted climate control or blank fascia of plastic where you’d normally expect to find a radio. Or maybe it was the blood-red roll cage lingering in place of the back seats that scared them off.

Further sacrifices included the front fog lamps, rear window wiper mechanism and heating, and nearly all sound-deadening. The only concession to safety was driver and passenger airbags – a big call for a regular car that was the first to be awarded a Euro NCAP five star safety rating. The bonnet was now crafted from carbon fibre and, underneath, the 2.0 turbocharged engine block has more exposure than an Only Fans channel – looking completely naked, shorn of any plastic dressing.

I imagine a lot of potential sales recruits failed to graduate from basic training as a result of this car. The rigmarole involved in shimmying into the seats and bolting up the six-point harnesses makes solving a Rubik's cube look like child's play. And then you realise you’ve left the door open and can’t reach the handle so you have to start the process all over again.

Once upon a time, I'd have fitted comfortably into aggressive seats like these, but nowadays it feels like only those with snake hips could fit between the Boa Constrictor grip of the side bolsters. The good news is the pain from my newly dislocated hip wears off as soon as the adrenaline kicks in. Up the ante as the fangs of the harnesses bite down and you immediately feel utterly connected to the machine and the drive - it’s as if you’ve become a stressed member of the chassis.

This completely re-frames your mindset. Every corner becomes a challenge to clip the precise apex and put fresh air between the inside rear wheel and road surface. The trouble is, the chassis is so capable and exciting that the standard 227bhp no longer seems to cut it – despite the weightloss upping the bhp/tonne by almost 20. You just know that the car can handle more without upsetting the apple cart.

Perhaps that's why this particular car has been mildly breathed upon to a conservative 260bhp. Despite Renault claiming power was unchanged from the regular R26, the exquisite optional titanium exhaust has to be worth a few horsepower as well as decibels – not to mention adding a healthy contribution to the weightloss too.

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