Interview: Gordon Murray on the tiny Shell Concept

Gordon Murray's T25 was one of the most creative yet rational – if geeky-looking – small cars ever. It used extraordinarily little resource to shift three adults around a city. And Murray wouldn't let it not be fun. It was the sum of his creative and ruthlessly efficient approach to engineering, boiled down to a tiny capsule.

But he's recently realised it was flabby and draggy and generally sub-optimal. He only found out because his team has now had another go. "We didn't think there was a big step to be made, but there was," he said.

The new car, internally called Project M, is now formally called the Shell Concept Car. That explains the colour scheme then. "Shell approached us," says Murray, "and there was too little time to start from scratch." So the team took the T25 as a starting point.

"Shell wanted co-engineering, not a lot of people doing their own thing. We asked 'How much could you save if we all worked together?' We worked closely with Geo Technology on the engine, and the Shell guys. We re-examined every component of the T25."

The T25's Mitsubishi engine got an extreme internal makeover by Geo Technology. Geo was founded by Osamu Goto, who was once in charge of Honda's Formula One engines. Engines that powered Murray's dominant late-’1980s McLarens. Small wonder Murray and Goto forged a lasting bond. And those engines that ran on Shell.

"The T25 was proof of concept for maximum downsizing," says Murray. But even he, one of the great dons of automotive dieting, was surprised how much more they lost for the new car.

"I was hoping for 40-50kg saving. And the guys got 80kg." The Shell Concept weighs a scant 550kg, or half a supermini. It's passed crash tests too.

The body uses his iStream Carbon process. This uses a steel frame with semi-structural carbon-composite panels filling the gap. The carbon fibre part is lighter but dearer than the type of composite the T25 used. "But we used recycled carbon so it's affordable."

And a word from the sponsors – the results of working with Shell. By using bespoke lube, the transmission and engine bearings and wheel bearings could all be optimised and in many cases reduced in weight as well as friction.

The engine was redesigned by Goto's team with the lubricants in mind, and uses ultra-light pistons, slimline con-rods and diamond-like carbon coatings, all in the name of cutting friction.

Everyone is careful to say 'lubricant' not oil. The stuff they use here isn't just refined from crude, it's made of specially synthesised molecules.

Then there were aero savings. The T25 has a Cd of 0.37. The new car is 0.29, which is staggeringly low for a car so upright – "a small, square box," he calls it. And remember its frontal area is also pretty minuscule, so overall drag is vastly less than a normal supermini.

Murray calls the new concept "an exercise in city mobility with existing technology – without the hassle, weight and manufacturing emissions of batteries and hybridisation."

So, bottom line, what are the potential savings?

He claims his iStream process cuts manufacturing energy (and hence emissions) by 60 percent over steel. And the manufacturing element typically accounts for 15 percent of a car's lifetime emissions.

It has also been run through real-world and official-cycle tests. Murray says it would use almost a third less fuel than a petrol supermini or hybrid. And it would be cheaper. Now, when did you ever see four people in a city car?

Of course it'd be a breeze in traffic because it's only 160cm wide and has a turning circle less than a London cab's. A cinch to park, too. It's 20cm shorter than a Smart, so can be parked end-on to the kerb. It's also by the way, 330kg lighter than a ForTwo (550kg vs 880).

That's a whole lot of compelling advantages in return for its undoubted resemblance to the Little Tikes Cozy Coupe.

Over its whole lifetime of manufacture and driving and recycling, Murray says it would need just half the energy of a small supermini.

Ironic really that it's been underwritten by an energy company.