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.

The engine seems possessed in this state of tune and there’s value in seeking out the redline, where it closes in on the limiter with a real hunger over the final 1,000 revolutions. The outright acceleration is very strong but the in-gear thrust is rabid – the echo chamber behind no doubt enhancing the feeling of thrust. Even coming off the throttle is fun as the wastegate releases an angry series of hisses and whistles.

Sadly, the sharp throttle response is heard, rather than felt, due to a rubbery throttle pedal with two-tier pressure resistance. During the initial travel, the pedal is far too light; then 50% of the way down, it firms up, almost like a computer prompt asking if you are sure you wish to proceed. Similarly, the other foot is also let down by the clutch with its skyscraper biting point.

However, both these pedal characteristics are typical of fast Renaults. Yet you never notice these minor flaws when pressing on – there is no hindrance to a well-executed heel and toe. Mercifully, the brake pedal escapes a similar fate by offering almost delicate progression and immediate anchorage when summoned with force. In comparison to the clutch and throttle, the brakes are a joy to modulate.

You’ll initially file the steering in the flawed control weights category too – but spend more time with the car and you’ll begin to appreciate it. The geometry is unchanged from the R26, so the .R is no great communicator, and the steering is certainly very light, with a nanosecond of built-in slack just off-centre that should’ve been eradicated in a car like this. Thankfully, the no-compromise rubber with its granite side walls increases the precision.

Placing the car quickly becomes second nature and, eventually, you'll realise you prefer the slower gearing of this early EPAS over many current systems, which choose to mask their deficiencies with instantaneous reflexes. The featherlight weighting also fades into the background when pressing on enthusiastically – much like the awkward pedals. You wouldn’t, however, say no to another minor tweak: a retrim of the wheel in full Alcantara.

The steering gives you the confidence to lean on the car elsewhere too. The operation of the limited slip differential is a world-class highlight. It's simultaneously both subtle and aggressive – subtle in your hands, yet aggressive on the line of the corner. Initially, the rear end feels rather skittish – like its skimming over the surface rather than gripping it – but work some much-needed heat into the rear tyres and the sensation disappears and the back axle also becomes a directional asset.

A gentle lift to tuck the nose in ever-so-slightly still happens very sweetly and progressively, despite the high level of grip. A benefit of the low mass combined with the stability of a wide track and that bolted-to-the-chassis feeling. Has a front-wheel-drive car ever offered so much exploitable adjustability on and off the throttle? A 205 Gti is – unquestionably – more tail-happy, and the differential in the mk1 Focus RS is far more aggressive, but few cars combine the two so harmoniously and with such driver encouragement. Afterwards, I realise all these multiple angles of attack have occurred with the dynamic stability control still on – I’ve been having so much fun I completely forgot it existed. Renualtsport's ESP calibration certainly has some wide tolerances dialled in.

The weakest link at speed is the gearbox. Renaultsport isn't renowned for robust gearboxes – ask any Clio 197/200 owner – and the one in the Megane has pitiful resistance. As such, the throw across the gate is limp and loose but, thankfully, it doesn’t object to being rushed.

You can’t help but imagine how much more enjoyable the car would be with one further extreme: an aggressive touring car-style CAE shifter. Still, it’s not like you need to be rowing through the gears to get this R26 shifting. Save for some low-down sluggishness, the power delivery is very strong; whilst the car tracks true and straight at full-tilt, no matter the surface. Furthermore, there’s also zero axle tramp, unlike some high power front-wheel-drive cars.

It’s not just the technical ability that elevates the R26.R. It’s the assault on all the senses: the plexiglass windows buzz in traffic and the unladen passenger harness zings to the rhythm of the titanium exhaust. The R888s pick up every loose stone available before firing them into the arches like tobacco buckshot. These are elements of driving that are increasingly being snuffed out across the board – ones that create another dimension of interaction with the drive and amplify the sensation of speed.

In the end, only 364 of the planned 450 production run for the R26.R were bolted together. Renault UK was bold in reserving 230 of that original allocation but, when the curtain fell, only 159 travelled across the Channel. It’s good to see, however, that Renaultsport hasn’t been burned by the experience – churning out two successors, even if the numbers produced decreased and the price massively inflated.

Owner Kristian has had the car for several years now and covers around 2-3,000 miles in the car annually – most of which is spent on or travelling to a track day. He praises the behaviour of the car at the absolute limit:

“In slower turns, you can lean on the brakes heavily and use trail-braking to alter your line and, as long as you aren’t heavy-footed, exit speed can be kept high and accurate. The car will understeer if you do get on the power too early, but you will rarely experience it on the public road.

“Where the R26.R really excels is on entry to fast corners. Why? The chassis is so neutral there is never any fear about what it might do. if you go in too fast, the car will drift with absolute neutrality, with all four corners moving in unison. And trail-braking at this pace? You can certainly adjust the car nicely – particularly in the wet – but, again, it’s all so controllable you can constantly play with how you drive to get the most out of the car.”

What's great about the R26.R – after you’ve gotten past all the impracticalities of strapping yourself in – is it doesn’t eliminate over 80% of the U.K’s road network – despite its track leanings. Its suspension – whilst not as supple as I’ve read to believe – still operates at a bandwidth that can just about cope with a ragged B-road. There’s no doubt the Megane prefers a smooth surface, but at no point does the body control become overwhelmed. The famously backed-off springs are clearly being counteracted by the rock hard sidewalls of the Toyo tyres and, although it might lose some of the outrageous grip, it would be interesting to try the R26.R on some more pliable modern UHP tyres. Renault in fact offered Michelin Pilot Sport rubber as an alternative to the Toyo’s on the order form.

Whatever your stance may be on the room-for-two-only hot hatch, the good news is you can feel every penny invested by Renault in this car – the expense in each and every modification and what it brings to the party. Yes, entering and exiting the car is a faff and, yes, it’s very tiring and wherever you go you always seem to be accompanied by the distant roar of a jumbo jet thanks to the tyres. It’s unlikely to be appreciated by a non-car-loving partner either and, during our brief stint, the driver's electric window threw in the towel.

You could also argue that a regular R26 offers enough of the thrills without sabotaging its civilised manners. But that misses the point. It’ll never hit you with the single-mindedness, the physical rawness, nor get the heart pumping, like the car with the extra dot R. It’s like comparing filtered Kentucky Bourbon to pure white dog moonshine. Some cars are designed to make you feel comfortable; some are designed to make you feel alive. This Megane is certainly one of the latter that's absolutely worth tolerating.

Renaultsport Megane R26.R stats

Engine

1,998 cc turbocharged inline-four,

DOHC 16v, max 6,500 rpm

Output

Power 227 bhp @ 5,500 rpm,

Torque 229 lb-ft @ 3,000 rpm

Layout / Transmission

Front engine, FWD

6sp manual, Torsen LSD

Weight

1,230kg,

Power-to-weight - 185 bhp/ton,

Torque-to-weight - 186 lb-ft/ton

Performance

0.60 mph – 5.9s,

1/4 mile – 14.8 @ 97 mph,

Top speed – 148 mph