Re-styling an icon is perhaps the biggest challenge a designer can face, especially when the task in hand is to update an enduring and automotive classic like the Mazda MX-5, of which more than 400,000 have been sold since its introduction in 1989. This, however, was the formidable task which faced Martin R. Leach, managing director in charge of Mazda's Product Planning, Design and Programs, and his design team.

Tom Matano's original design is evocative of the great British sports cars of the mid-1960s, but without parodying them or appearing to be a cliché ridden pastiche - with obvious retro themes that would easily and quickly date. It was - and still is - a fresh design, light and nimble both in appearance and on the road. These were all cues which Mazda's design team had to convey without losing the MX-5's classic qualities of speed, style and fun. As Martin points out, the market has changed since the original car appeared. "We re-energised that sector, but now there are rivals like the MGF and Fiat Barchetta to take into account."

It would have been easy and, perhaps, the obvious route radically to change the MX-5's architecture or make it larger, but Martin and his four design teams based in Hiroshima and Yokohama in Japan, Orange County in California and Frankfurt, Germany, quickly learnt that the enduring charm was its simplicity and compactness.

Top of potential customers' wish lists were the inevitable cup-holders, more trinket space in the cabin and a boot large enough to accommodate a pair of golf bags. The new MX-5 achieves all of those requirements without having grown - it's the same length as the outgoing model and only five millimetres wider. Re-packaging the battery and spare wheel not only gave room for the two golf bags, but meant Mazda's engineers could increase the rear suspension's stroke, lower the centre of gravity and change the suspension trail to achieve an even better dynamic package than its predecessor with lower roll centres.

"This is one area where the design and engineering philosophies came together to complement each other to produce an excellent overall programme," says Martin. If, then, the new MX-5 isn't physically larger than the original why does it appear so? According to Martin it's all down to subtle re-profiling of the fenders to give them more crown. "The major trend was this sense of stature we wanted to give the car. It's got more presence, that was a very conscious decision and to achieve that we put more crown into the fenders and more visual mass into the vehicle to give it a more 'tready' feel."

Looked at alongside its forebear the new car is the same but different. The most obvious external change is the absence of distinctive pop-up headlights which had become an MX-5 signature. Now they are replaced by a pair of ellipsoid lenses giving the car an even more feline face, but with improved aerodynamics, reduced complication and - with an eye to potential legislation on pedestrian impact - improved safety.

What hasn't gone, though, is the distinctive frontal air intake and the rear lamp treatment. "After all," says Martin,"that's the view most other road-users get of an MX-5." Meanwhile a new duck-tail lip and raised centre section to the boot enhances aerodynamic performance. Because sports cars' interiors can be exposed, their styling becomes an extension of the exterior design package, so great attention has to be paid to the detailing of instrumentation, the fit and function of the switch gear and the visual appeal and tactile nature of the surface materials.

As with the rest of the car, Martin and his colleagues have stayed faithful to the originals' concept with eyeball vents, but have moved the whole concept one stage further by adopting Mazda's T-shaped instrument panel with white on dark-blue instruments.