John Simister: Learning the Gordon Murray formula

This new facility, called Gordon Murray Automotive – the existing Gordon Murray Design operation continues elsewhere (Shalford) in Surrey for now – will make use of Murray's iStream system of car production, using a tubular frame with bonded composite panels between the tubes. Murray has been piquing car manufacturers' interest in this system for a while – it grew out of the 'Minibug' he devised in 1970, albeit with steel panels instead of composite ones – and it underpins the new TVR Griffith. But more intriguing yet is Murray's plan to make his own diminutive two-seater coupé, bearing the IGM brand that represents his initials (first name: Ian).

The plan was revealed at the 'One Formula' exhibition of Murray's creations, 38 of them, held at the new GMA factory at the beginning of this month. Among those 38 were obvious candidates such as Formula One Brabhams ('fan car' included) and McLarens, every variant of the McLaren F1 road car, a recreated Minibug, the Duckhams-Ford Le Mans car, an Alfasud-powered Midas, the motorbike-powered Rocket and the new TVR, plus his T25 three-seater mini-car of 2010 which first demonstrated the iStream process. And of course his first design, a Lotus Seven-like device also called IGM.

Also on show, significantly, were cars from Murray's own garage, over 20 of them with a very obvious theme. That theme encompasses compactness, lightness, agility and modest power. Two red Lotus Elans, one of them an S3 Coupé owned for three decades to remind him of the first car he bought after arriving in the UK from South Africa, set the tone for a collection which also includes a BMW 700, a 'frogeye' Sprite, a couple of Fiat 500s, a Honda S800, a Mini, a Smart Roadster, a Lotus Elite (Type 14), a Cortina GT, diminutive racing Alfas and Abarths, and more besides.

So you can see the thinking behind the new coupé, which will use aluminium for some of its structural tubes plus carbonfibre composites in a new 'iStream superlight' process. The body/chassis structure will weigh about half as much as its pressed-steel equivalent, and a prominent design feature seen on the teaser image is a roof-mounted air scoop for the mid-mounted engine. Knowing Murray's liking for the idea of the Smart Roadster (if not its recalcitrant two-pedal transmission), a three-cylinder engine well under a litre in capacity, but turbocharged, is the likely source of motive power and will be enough to give the IGM potent performance.

This new project cystallises what Murray has been propounding for many years. Back in 2010 I spent a fascinating day with him at Gordon Murray Design, to be further indoctrinated with the lightness mantra to which I was already a convert. He arrived in that red Elan S3, I in my Peugeot 205 GTI, compact and agile lightweights both. 

He drew a 'virtuous circle' of lightness on his board, in his precisely artistic hand, while berating the overweight cars of modern times. 'It has really annoyed me over the years,' he said. 'Weight is a designer's enemy. Acceleration, braking, cornering, it's bad for all of them. You could go the Bugatti route – the Veyron has a lot of power but it weighs two tonnes – but you can never have transient agility with a car like that.' 

He talked of the need not for outright power but for a good power-to-weight ratio or, better still, torque-to-weight. From the 'lightweight' starting point of his circle his felt pen drew round 90 degrees to 'small powertrain', then round a further 90 degrees to 'small components'. If said Murray, the structure and the powertrain are light, then the suspension has smaller loads to bear and the brakes have less energy to dissipate. So both can be downsized.

If a body-in-white could be 50kg lighter, Murray had calculated, the complete car could be 100 kg lighter. 'In particular,' he said, 'the wheels and tyres can be smaller. If there's a killer, it's four bloody great heavy flywheels. They spoil acceleration and braking and they kill the secondary ride.'

Ninety degrees further round, Murray wrote in 'performance and efficiency'. Here, where the circle reaps the benefit of what has pre-traced it, Murray talked not just of acceleration, speed and low fuel consumption but of the 'transient stuff, feedback, that agility stuff that makes a car fun to drive.' And then the circle was completed.

For fun, he then reeled off the mass-numbers of the favourite flyweights in his garage, numbers to bring quickly down to earth anyone who thinks creating a sub-one-tonne supermini is something to celebrate. Here's a selection: Smart Roadster Coupé, 830kg. Lotus Elan S3 Coupé, 690kg. Austin-Healey 'frogeye' Sprite, 650kg. Porsche 550 Spyder, 550kg. Fiat 500, 500kg. Rocket, 370kg. 

Murray, of course, also designed the Mercedes-McLaren SLR while at McLaren, and is not proud of the result. 'The McLaren F1 weighed 1,140kg. Compare that with the SLR. It ended up at 1,630kg despite its carbonfibre tub. It had seven radiators, which made the powertrain 85kg overweight.' The circle duly did its stuff, but sinfully this time.

That certainly won't happen with the little IGM micro-supercar. It will be compact, agile and driver-pleasing like a Lotus Elise but more so, and an antidote to Murray's dislike of today's too-wide, too-heavy, too-powerful, too-expensive supercars. Sounds absolutely brilliant to me.