McLaren MP4-12C

I found an interesting article on Ricardo's website related to the MP4-12C engine. Link to the pdf were the article copied below has been published.

In some ways the M838T is a classic design, a 90 degree V8 with a flat-plane crank and four valves per cylinder. But despite that superficial orthodoxy and despite its extraordinary robustness, there is nothing ordinary about the specification of the new McLaren V8: in fact, it is cutting edge in almost every respect. The engine has the lowest CO2 emissions in its class – just 279 g/km – and meets both EU5 and ULEV2 emissions standards. Power output is a thrilling 600 PS at 7500 rev/min, matched by 600 Nm torque at 3000 rev/min. Thanks to clever fundamental design the compact cylinder block has an exceptionally low mass: not only are the main and lower bedplate crankcases sand cast in aluminium alloy, but so are the top-hung, wet cylinder liners, a feature which saves an additional 4 kg compared to conventional cast iron liners. Careful targeting of the sand cores helps keep the weight down too, and the finished assembly comes in at just 36 kg. The flat-plane crankshaft allows a smaller counterweight radius and, combined with the short stroke, this allows a low block height of just 201 mm and a crank-to-ground centre line height – important for road-holding – of only 121 mm. Dry-sump lubrication also allows low positioning of the engine in the chassis and this helps create the lowest possible centre of gravity for the MP4-12C. 

So-called picture-frame sealing eliminates T-joints in the crankcase assembly and thus the risk of oil leaks, while high levels of feature integration (as opposed to separate components and covers) not only reduces component count and weight, but also the likelihood of faults such as coolant leaks.

Ricardo’s analysis tools played a crucial role in designing a high-quality and robust engine, and their use in the development of the cylinder block is a particularly good example. “We did encounter some difficulties and we are quite open about that,” admits Yates. What is important, though, is how those inevitable hurdles were identified and quickly overcome. Early on in the development phase there were some instances of liner cracking, for example, but by looking closely at the clearances, the support and how the liner was loaded and clamped, these problems were quickly eradicated.

Pumping losses (the energy expended pumping air into and around an engine) are a major source of wasted energy and increased fuel consumption. In the new V8, Ricardo isolated crankcase bays one and four from two and three and also isolated the timing chain case from the crankcase bays. This prevents the transfer or, literally, the pumping, of air between the bays and through internal passages: this significantly improves both power and fuel consumption at high speeds.

Top end design

The cylinder head is one of the most important assemblies in any engine, and its design makes a particularly important contribution to the performance, emissions and fuel consumption characteristics. In this case, each of the two cylinder heads has double overhead camshafts, each camshaft being fitted with its own phaser. Like the block, the cylinder heads are optimized for weight, single-piece plastic cam covers giving a net weight saving of 2.3 kg and an aluminium rocker carrier and thin-wall spark plug tube saving a further 2.5 kg.

The narrow included valve angle reduces the width (and weight) of the head and an integrated housing for the variable valve timing gear enables compact oilways and minimises the overall length of the heads. Again, from the perspective of quality and robustness, single-plane oil sealing rules out oil leaks.

Needless to say, the head design is minutely optimized to maximise performance and minimise fuel consumption and CO2 emissions. Exhaust valve size is maximised to avoid gas flow restriction and to increase the available turbine energy. Intake ports are designed to provide excellent gas flow while retaining good tumble characteristics for efficient fuel-air mixing. The high flow rate reduces pumping losses and the tumble helps low-speed combustion as well as improving fuel economy at high speed. The quadruple cam phasers improve response, torque, power and fuel economy throughout the engine speed range.

The valvetrain features end-pivoted finger followers and a single ‘beehive’ design of valve spring, the low mass and high stiffness of which provides accurate valve control at high speed while keeping forces – and thus frictional losses – to a minimum. The cam profiles were also designed to improve these characteristics, with the use of VALDYN at the design stage helping eliminate any risk of loss of contact with the camshaft, spring surge or valve bounce.

The head casting went through a number of development phases after analysis of the first version revealed the potential for excessive temperatures in the exhaust bridge. Thermo-mechanical finite element analysis made it possible to evolve the design of the cooling passages and head gasket shaping to optimize the targeting and velocity of coolant jets, as well as making components easier to manufacture.

Cooling: critical for efficiency

Temperature control is critical to engine efficiency, and for this reason the V8 has a three-plate electrical thermostat which allows higher running temperatures during normal driving and ensures operating temperature is reached very quickly. The three-plate thermostat is effectively three-way or with three valves, so the unit can graduate cooling, something that is especially important during warm-up or during part load. It offsets the huge thermal changes between an engine capable of idling at a few hundred revs producing minimal power and maximum power of 600 PS at 7500 rev/min.

On that note, even the idle speed of the V8 was scrutinised and reduced to 600 rev/min from its initial target of 850. “The idle speed was important and driving that down was something we found we could do,” says Yates. “It benefits CO2 emissions and also the noise characteristic of the engine.”

Clearly, the sound quality of a supercar engine is crucial and a considerable amount of work was carried out to get the balance just right both inside and out. Because turbochargers significantly mute the wave form of intake noise, a sound transmission system incorporating a resonator was included to pipe sound to the cabin. The design of the exhaust system also took into account sound quality as well as efficiency. Like the cam covers, the entire inlet manifold is also moulded in plastic, reducing weight at the top of the engine to lower the centre of gravity.

The test regime was thorough and unforgiving. Five thousand hours of basic testing on seven dynamometers running in shifts served to check and validate every aspect of the new engine – from performance and emissions to mechanical durability testing of individual components. The work included thermal shock testing – the engine temperature rising to 116 Celsius at full power then being ‘crashed’ back to 20 Celsius using chilled coolant – a brutal process repeated hundreds of times to verify fatigue performance as well as severely checking the sealing of joints and components.

A further 3000 hours simulating the famous Nürburgring Nordschleife race circuit using real data logged during track testing there gave the equivalent of 73,000 km on-track driving. At the same time, major component and system-level testing was being carried out elsewhere on rigs in a combined test plan between Ricardo, McLaren and their suppliers. Final vehicle testing comprised more than 1,000,000 km on a mixture of road and track at Nardò, Idiada and the Nordschleife. The final stage prior to production was the building of 95 ‘made like production’ prototypes using production sequences and tools.

At the end of all of this, and just 18 months from the start of the collaboration with Ricardo, a unique new engine was born, possessing spectacular performance and emissions and easily meeting the high-level goals set by McLaren based on the exacting expectations of its very discerning customer base. The MP4-12C that it powers defines a completely new segment within the premium sports car market. To build a brand new car is a challenge; to build a brand new high-performance sports car that is ground-breaking, efficient, high-quality, lightweight, practical, dynamic, safe, comfortable, and visually arresting is a greater challenge still. McLaren – with help from Ricardo and other highly innovative supply chain partners – looks to have achieved this in considerable style.

And for Ricardo employees and investors, the new High Performance Assembly Facility also provides a proven approach for taking high performance, Ricardo-developed products into production applying world-class quality principles and practices within a lowvolume setting. As such, the facility is both a model factory and a business template that will be of keen interest to many potential customers seeking to add a halo, high-quality, performance product to their model line-up.

Reports of problems on early deliveries can be found everywhere on internet. It has been recognised officially in a letter sent by McLaren to its first customers. Read below:

"It is with both pleasure and frustration that I am writing to you at this early stage in your ownership of the McLaren MP4-12C. Pleasure because you are now part of our McLaren family and have bought into what I believe to be both the best car in its class, and the most exciting automotive adventure in decades; but frustration on a personal level because we have not yet been able to deliver on the high standards that we have promised and that should come as given with the McLaren brand. We have built up our McLaren businesses over the past decades based on our determination to be the best, and that is no different for the MP4-12C and all of our future cars.
When we began working on the MP4-12C, we were determined to deliver not only the best car in its class, but also the best ownership experience. We believe that the performance and driving experience of the MP4-12C is world class. However, along the road to achieving our goals, we will experience challenges. As you will have already heard from my staff, we are experiencing some early software bugs resulting in unnecessarily sensitive warning lights, battery drainage in certain conditions and IRIS performance issues. My team and the McLaren retailers are working with the pace and intensity that the McLaren brand demands to fully resolve these bugs rapidly and effectively to ensure that any inconvenience to you is kept to a minimum. It will however require your 12C to come back to your dealer at some point so that we can upgrade the software on your car. I hope that the way we deal with these issues sets us apart and is to the standard you would expect from McLaren.
We know you share our passion for racing, therefore as a token of my appreciation for your support during this time, your retailer will be giving you a pre-release copy of the new 'McLaren: The Wins' coffee table book. I hope that you enjoy the stories behind what makes McLaren winners and that this, in some small way, reminds you how much we appreciate your faith in us. We want to win on the road as well as the track, and we will work tirelessly to achieve this goal.
I would like to extend my personal thanks for your support and patience at this time. Should you have any questions, please contact your retailer in the first instance. Alternatively, please call my staff at McLaren Assistance on 0800 975 8285."

Source here.

Pendant quatre ans, trois cents techniciens ont passé en revue chaque détail pour que la MP4-12C soit meilleure. Selon la célèbre règle des 5%, les pièces, une première fois validées, ont été reprises de manière à être de nouveau allégées de 5%. C’est ainsi que l’on arrive à un vrai résultat, en ne lâchant rien. Pour s’imposer, face à une concurrence installée de longue date, la MP4-12C dispose d’armes innovantes dans son segment, telles qu’une coque carbone, une suspension réactive et un correcteur de trajectoire de courbe issu de la Formule 1. La 12C est plus rigide tut en étant plus légère, plus compacte mais plus habitable, plus puissante mais moins polluante. Ses points forts ne sont entachés d’aucun point faible. Parce que ses concepteurs n’ont rien laissé au hasard. Voyons cela plus en détail.

Architecture

La rivale la plus proche de la MP4-12C est la très appréciée Ferrari 458, elle aussi dotée d’un moteur central arrière. L’Italienne est la descendante d’une longue lignée, initiée au milieu des années 70. Son gabarit est proche de celui de la McLaren, mais cette dernière dispose d’un avantage de puissance de l’ordre de 5% et d’un couple plus généreux de 11%. L’Anglaise est aussi plus courte de 18mm alors que son empattement est plus long de 20mm, avec à la clé un habitacle plus généreux. Ses voies et sa carrosserie sont plus étroites de 25mm, caractéristique qui rend la vie un peu plus facile dans la circulation de tous les jours.

McLaren fait état d’une masse de 1338kg à sec, ce qui veut dire que la 458 est 50kg plus lourde. La 12C tire pleinement avantage de sa cellule en carbone qui n’accuse que 75kg tout en assurant une rigidité très élevée.

Châssis

La cellule centrale monocoque fait appel à un procédé de fabrication plus rapide et moins coûteux que celui qui a été employé sur les supercars. Le rythme annuel initial de production est de mille unités, mais il pourra être porté à quatre mille lorsque la gamme aura été complétée, jusqu’à quatre modèles, sur la même architecture châssis. La concurrence a opté pour des structures en acier ou en alu, plus lourdes et moins rigides.

D’après Claudio Santoni, le ‘’Monsieur carbone’’ de McLaren, le choix technique s’imposait au bout de trente et un ans d’expérience en la matière. Le moulage d’une pièce a ses avantages : ‘’Nous avons appris avec la SLR qu’en multipliant les pièces et en les assemblant, on perdait de la rigidité.’’ On a également tiré profit du procédé pour concevoir un habitacle plus fonctionnel : ‘’Sur un châssis alu, on est obligé d’avoir un élément de rigidité très encombrant, derrière les passages de roues avant, souligne de son côté Neil Patterson, chef concepteur. Cela vous oblige à reculer le pédalier dans l’habitacle.’’ Il convient également de remarquer que le système de ventilation sur mesure, plus compact, a permis de pousser un peu plus loin cet avantage et d’implanter de manière plus idéale la colonne de direction et les sièges, en parfaite harmonie avec le pédalier.

La coque est complétée par une structure auxiliaire déformable à l’avant ainsi que par un berceau moteur à l’arrière. Ces bâtis qui reçoivent les trains roulants sont réalisés à partir de profilés en alu.

Suspension

Les trains avant et arrière s’articulent autour de triangles superposés et combinés à ressort. Leur originalité réside dans la gestion interactive de l’amortissement qui contrôle le roulis et le tangage, tout en préservant le confort. Le système opère sur trois modes au choix : Normal, Sport et Piste.

Les amortisseurs communiquent par une liaison hydraulique longitudinale et latérale. Des capteurs mesurent plongée, cabrage, roulis et lacet, et commandent une correction immédiate. La pression est générée par le surplus produit par la pompe de direction lorsque les roues sont droites. Cette énergie est stockée dans les sphères, façon Citroën, et consommée en phase d’appui. Cela procure à la 12C une efficacité doublée d’un confort ‘’d’un autre monde’’, selon l’expression même des ingénieurs.

Moteur

D’après Richard Farquhar, responsable du groupe motopropulseur, l’idée de faire appel à un V8 compact suralimenté allait de pair avec le châssis carbone. Il a été question, au tout début, d’un V8 atmo signé AMG, mais la séparation entre Mercedes et McLaren a très vite éliminé cette option au profit d’un choix plus moderne et plus efficace. Le V8 3,8 litres double turbo est inédit. Il a été conçu chez McLaren et finalisé avec le concours de Ricardo pour son industrialisation.

‘’Dès que nous avons défini l’architecture de l’auto, nous avons su qu’aucun moteur dérivé de la série ne pourrait rentrer. Le V8 offrait un compromis idéal. Il est plus court qu’un V10 et garde un lien avec la compétition.’’ La cylindrée de 3,8 litres garantit un volume unitaire générateur de couple et un faible encombrement. Lorsqu’il est en place, ce moteur à l’air minuscule et son carter sec l’a beaucoup abaissé. C’est un 4 soupapes double arbre, à entraînement par chaîne. Il ne pèse pas plus de 150kg et son système de fixation ingénieux a permis de le rapprocher de la cloison pare-feu. On a ainsi gagné 3cm sur l’empattement.

Les accessoires sont entraînés par des arbres placés le long du bloc et l’espace disponible au centre du V a été pris par l’échangeur huile/eau, un filtre à huile et un réservoir sous vide. L’injection directe a été jugée inutile pour atteindre les 600ch avec un couple qui se maintient à 61mkg entre 3000 et 6000 tr/mn. Elle fera partie de développements futurs.

La tubulure d’échappement est remarquablement compacte. Chaque collecteur en inox est relié à une paire de catalyseurs montés en tandem. Le tout débouche dans un gros silencieux muni de deux sorties. Une ligne allégée, réalisée dans un alliage nickel-chrome utilisé en F1, fait partie des options. Le son qui arrive aux oreilles des passagers est produit par un boîtier logé dans l’admission et régi par la gestion moteur-boîte. La 12C peut être aussi discrète qu’une berline et se faire stridente en mode sportif.

Transmission

La boîte 7 rapports à double embrayage marie une pignonnerie Graziano et un carter McLaren destiné à mieux épouser le bloc moteur abaissé. La commande à palettes au volant est montée sur pivot de manière à changer les rapports d’une seule main, comme sur les F1 de la marque. Dans le même registre F1, on trouve cette fonction spéciale de l’ESP qui freine la roue intérieure en appui pour corriger le sous-virage. Cet artifice a été célèbre en son temps (avant d’être interdit) sous le nom de cornering ou steering brake. D’après les ingénieurs, on a le même effet qu’avec un différentiel vectoriel mais avec 20kg en moins.

Côté gestion de boîte, on dispose d’une présélection en actionnant partiellement la palette. Et l’on peut descendre plusieurs rapports lors d’un gros freinage grâce à une pression prolongée de la palette. Les Ferraristes connaissent. Il va sans dire que les modes auto, faible adhérence et launch control sont présents.

Roues et freins

Pour préserver le confort des passagers, la McLaren reste dans la norme avec du 19 pouces à l’avant et du 20 pouces à l’arrière. Les Pirelli PZero utilisent une gomme tendre spécifique adaptée à la suspension ‘’Proactive’’ qui assure un meilleur travail. Le freinage de série est composé de disques en fonte avec bol alu (8kg de mieux que le tout acier). Les disques carbone/céramique sont en option. Ils permettent de gagner encore 3kg.

Aérodynamique

Simon Lacey est amplement satisfait du travail des designers qui ont respecté ses besoins. Jusqu’à l’élégante taille cintrée de la caisse qui ne perturbe pas le fonctionnement des entrées d’air latérales. Celles-ci, avec le museau et ses entrées périphériques, ont fait partie de ses soucis majeurs, au même titre que l’appui et le Cx. A ce sujet, McLaren ne souhaite pas communiquer de valeurs.

Le débourrage des passages de roues a été aussi particulièrement soigné. La 12C dispose d’un fond plat et d’un vrai diffuseur. Elle génère un appui de 100kg à 240km/h, répartis de la même façon que les masses de l’auto, soit à 57% sur l’arrière.

Le souci de détail a été payant, à l’exemple du profilage des supports de rétroviseurs et du bras d’essuie-glace qui a permis de réduire le bruit.

Le vrai truc de la 12C est son aérofrein, cette aile d’avion inversée, à l’arrière, qui se relève jusqu’à un angle de 57° et dont la forme est prévue pour ne pas trop engendrer de contrainte mécanique. Ce dispositif présente l’avantage de stabiliser l’auto à la décélération.

66 mulets et 300 gars

Il aura fallu quatre ans pour développer la 12C, un an de plus que la moyenne, parce que l’on ne partait d’aucune base existante. Et un investissement de 875 millions d’euros.

Pas moins de 66 mulets ont été construits, entre 2008 et 2011, avant d’arriver à la version finale. Sans compter les préséries et les modèles destinés au marketing. Toutes ces autos, réalisées à l’unité, ont coûté bien plus cher que le modèle livré au client.

Les premiers tests de suspension ont été réalisés avec une Ultima qui présentait l’avantage d’être discrète et d’un format compatible. Se sont ajoutés les MV, ou Mule Vehicles, un peu ‘’brut de fonderie’’, qui ont permis de mettre au point certains organes. Les Concept Prototypes, plus représentatifs, ont été les premiers à disposer d’un châssis plus proche de la réalité. Ils ont coûté plus d’un million d’euros pièce. Ont suivi les Experimental Prototypes, ou XP, habillés d’une vraie carrosserie et réalisés à partir d’un outillage pré-industriel. C’est avec ces autos que les essais intensifs ont été menés, comme une endurance de 10000km ‘’à fond, à fond’’ à Nardo et des séances répétées sur le Nürburgring. Sans oublier en parallèle des sessions de torture au banc des organes principaux, sur modélisation de tests réels. C’est également avec les XP que l’on a procédé aux crash-tests.

La génération suivante de mulets a été baptisée VP ou Validation Prototype. C’est l’avant dernier stade avant les Production Prototypes, assemblés sur chaîne.

Chez Ford, il aurait fallu trois mille personnes pour mener à bien pareil projet. Chez McLaren, ils ont été trois cents. Chapeau.

Publié dans le numéro de Mars/Avril 2011.

Ever wondered how to tell an MP4-12C prototype to the real thing? Matt Saunders finds out while learning more about how the car is engineered.

Right now, there can’t be many more exciting places to work anywhere in the global motor industry than Chertsey Road, Woking. That’s because McLaren Automotive is about to produce. The paint is now dry on the company’s new £40 million McLaren Production Centre, from where, in a matter of weeks, the MP4-12C supercar will begin to roll out to expectant customers. And so, after four years of intensive design and engineering and close to £750m of investment, the world is about to discover exactly how good one of the most anticipated sports cars in history really is.

But what if the genesis of this incredible car stopped now, before even ‘job one’ – the very first customer order – appeared complete at the factory shutters? What would Ron Dennis have to show for all that invested money and effort? The answer, aside from so many hard drives’ worth of digital ‘intellectual property’ and a very large, very quiet factory, is a warehouse full of prototypes.

It’s by the design, specification, assembly, testing and subsequent disassembly of prototypes like these that all new cars find their way to the road. These are the cars that bridge the gap between the designers’ vision and the finished product. There are prototypes conceived to test the effectiveness of primary structural systems, to carry out engine and gearbox proving, for dynamic and aerodynamic development, for crash testing and active safety set-up, for the configuration of onboard electronics, for hot and cold-weather proving, for the verification of final production design and more.

You’d be amazed at how many ‘mule’ versions of the MP4-12C McLaren needed to build before it could even contemplate building the very first customer car. You’d be even more amazed, believe me, at what they cost, and at the provenance of some of the parts that lurk beneath the surface.

Standing in one of the McLaren Technology Centre’s impossibly clean workshops, we’re currently looking at four of those prototypes. The nearest one to us is painted, trimmed, flawlessly finished – indistinguishable from a production-line 12C, really. The farthest, by contrast, is outwardly indistinguishable from an Ultima GTR kit car. And we’re about to find out exactly how McLaren progressed from one to the other.

Masters of disguise

“We’ve built 66 mule cars to date out of the workshops at the MTC,” explains McLaren programme director Mark Vinnels. “We’ve got eight more to go, followed by a further 16 ‘marketing cars’ – and that’s all before job one starts at the factory. The very earliest were little more than a running chassis, while the latest are built using production-ready parts and tooling; those ones don’t cost an awful lot more than production-line cars.”

McLaren called its very earliest prototype MP4-12Cs, built at the beginning of 2008, ‘MVs’, short for ‘mule vehicles’. There were three of them: two for very early powertrain work, the other for the earliest proving of McLaren’s Proactive interlinked hydraulic roll-control suspension.

“Our suspension car was photographed a few times,” explains Mark, pointing to the black Ultima-based chassis at the far end of the room. “We needed a car of roughly the right size and weight to experiment with this active suspension set-up, and the Ultima was perfect.” Must have delivered a frisson of amusement, too, throwing journalists and spy photographers so far off the scent with a mule car as left-field as Ultima.

After the MVs came the CPs, or concept prototypes, represented in our photos by the black and white car. These were the first MP4-12Cs that were vaguely representative of the final car in terms of underbody and outward structure. They hit the road fully two years ago, before the final production design of the car has been made public, wearing heavy disguise.

“We had several early carbon Monocells pressed for the CPs,” says Vinnels, “and we mainly used the cars to explore our structural options. We’d already committed to a carbonfibre tub and knew we wanted to make it as light as possible, but not by compromising stiffness. And so our CPs had tubs varying from 80-something kilos at their heaviest, down to 69 at their lightest.” They were expensive, too, costing McLaren up to half a million pound each.

A closer look at the zebra-striped concept prototype shows some intriguing details. From a distance it’s clearly a 12C, thanks largely to the distinctive air intakes on each side, but the closer you get, the more differences you see. The CP has got swollen front and rear bumper, Perspex windows and door handles that could have been lifted from an ironmonger’s bottom drawer. It’s something of a lashed-up masterpiece, but it evidently served its purpose.

Come 2009, after the CPs, came the first breed of almost undisguised prototypes: the XPs, or experimental prototypes. Vinnels says these were “mules with the right body on”, like the all-black 59-plate mule in our photos; they were ‘real’ cars built with prototype tools on the old SLR line at the MTC. It was in one of these that McLaren hotshoes Lewis Hamilton and Jenson Button got their first taste of the MP4-12C.

The XPs were also the first 12C prototypes to hit the development trail in earnest, running engine, chassis and electronics calibration tests all over Europe and doing hot and cold-weather tests. McLaren’s proving programme took in the IDIADA proving ground in Catalunya, as well as Nardo in Italy, the Paul Ricard circuit in France and the Nürburgring in Germany. It included a 10,000km flat-out handling test at Nardo conceived to push the MP4-12C’s chassis to the limit of its capabilities and durability, and was driven in shifts. It also included an intriguing 5000km powertrain test at IDIADA that Vinnels calls the ‘IDIschleife’. “We data-logged all the throttle positions, braking positions and gearchange points from a flat-out lap of the Nordschleife,” he says, “and then repeated them on the high-speed bowl at IDIADA, over longer than we could have at the ‘Ring. It was a great stress test for the

engine and gearbox.”

It was with the XPs that McLaren’s crash testing programme for the MP4-12C also began. “We had to be sure that the basic underbody structure of the car was strong. Structural parts like the Monocell, the car’s primary crash structures and the body-in-white around the bulheads – they’re all long-lead items. It takes a long time to change their design, and doing that can have all sorts of knock-on effects on the design of other components, so if you do need to redesign anything major, you need to know early on.”

“Altogether, we threw 12 cars at the wall,” Vinnels goes on. “We’ve done well over a hundred barrier tests and more than 250 sled tests with all kinds of offset barriers and poles, and at various speeds. And we’re very happy with the car’s crash performance. The basic passenger Monocell is sufficiently strong that we could recover several of the tubs used in one test, fit new crash members and re-use them.”

Uncompromising approach

Standing in front of the final prototype in the workshop, Vinnels explains the raison d’être of a validation prototype, or VP. “These cars are built using production tooling; they allow us to start assessing and fine-tuning material quality and fit and finish on the car, as well as to continue tuning electronics, driving characteristics and NVH.

“We’ve built 22 VPs to date, having started in January 2010,” Vinnels says, speaking back in December, “and by the time we get to number 30 we’ll have arrived at a car we’re pretty much ready to sign off.”

There is one further prototype stage, he explains, during which McLaren will make a number of production prototypes, or PPs. They’ll come off the factory line just like any customer car, allowing the team to validate their quality and performance one last time. If the MPC production cycle isn’t quite right – if designed-in, systemic problems are adversely affecting build quality – these cars will allow McLaren to remedy the situation without disappointing customers.

So is there any part of that development process that McLaren could have skipped or trimmed, you wonder, without adversely affecting the finished car? Four years seems like an unusually long gestation, after all.

Not according to Vinnels, who joined McLaren in 2005 and therefore oversaw the whole thing. “The fact that we were starting from scratch with the 12C, without any proven componentry we could carry over from a previous model at all, added a year to the process,” he says.

“We’ve also been pretty uncompromising in our approach, and that’s added time in. We couldn’t find a ventilation system for the car that was compact enough, and yet good enough to meet our requirements, for example. So, for the sake of 50mm of overall width, we developed our own. We’ve been continually focused on weight, too; the original specification was for 20kg of sound-deadening NVH insulation in the car but, after some experimenting, we’ve ended up with just 7kg.” You get the distinct impression that engineers with Vinnels’ experience (he has stints at British Aerospace, Lotus and GM on his CV) aren’t in the habit of wasting time and money without gain.

“When I step back and look at the car we’ve created, I’m proud of the work – even more proud of the team that did it, though,” he says. “Ultimately, there’s only 300 of us; Ford would have 3000 people working on a project like this. When you guys finally get to drive this car, I’m hoping you’ll agree that we’ve done a good job.”

Article published in Autocar special edition dedicated to the MP4-12C