GENEVA, March 11 (Reuters Life!) - Shiro Nakamura likes to think that designing cars is like making music.

As Nissan Motor's chief creative officer and an active cello player, Nakamura should know.

Since he began heading up design at Japan's third-biggest automaker nine years ago, the youthful 57-year-old has transformed the company's image as a technologically savvy but generally form-blind outfit into one known for its design flair.

At Nissan, which also makes premium cars under the Infiniti brand, his gig involves a range of music, he says.

"Luxury cars are like classical music: you have to respect certain rules - otherwise they will not be accepted," Nakamura said, motioning to the models displayed at the Infiniti stand at the Geneva International Motor Show.

"The Nissan brand is more like jazz, pop or rock: you can ignore the rules."

Up to a point. One of the biggest challenges car designers face is creating a uniqueness that is evident across the line-up and at the same time, appeals to the masses.

"Nissan draws hints from contemporary Japan - things like animation, and 'manga' (comics)," Nakamura said.

The bubbly Pivo2 electric car concept, which has an egg-shaped cabin nestled inside four small, swivelling wheels, is a perfect example.

"With concept cars, we pull out all the stops - it's very cute and Japanese. You won't see anyone else doing something like this," he said.

"But with mass-production cars, you want to tone it down without losing the essence, so they can be accepted by consumers," he said, referring to cars like the Micra/March subcompact, which, with its rounded silhouette and 'cuteness', shares a certain aesthetic with the Pivo.

Within Nissan, there is also a hint of the other extreme of Japanese pop culture: robot cult-comics like Gundam, in the iconic GT-R sports car remodelled this year.

"The GT-R is a total muscle car. It's completely unusual in Europe, very manga-like and mechanical, like Gundam," Nakamura said.

"It's not traditional in any sense - not elegant or aerodynamic. And that's okay, because this isn't a volume seller, and shouldn't be."

Infiniti, on the other hand, must have the elegance and universal characteristics that appeal to luxury goods consumers worldwide, he says.

"Infiniti's design, unlike Nissan's, is global and more inspired by nature," said Nakamura, who designed for truck maker Isuzu Motors before being recruited in 1999 by Nissan-Renault CEO Carlos Ghosn.

"The reason is simple: customers seeking luxury have a common eye all over the world. It's the same with fashion."

The four cars at the Infiniti stand - the brand-new FX50 sport utility vehicle, the G sedan and coupe and EX crossover - do share an elegance, dynamism and sportiness for which Infiniti is known.

But without the apparent Japanese-ness that some customers may want, it could be a tougher sell in Europe than its mass-market cousin.

"Europe is a very very tough market for (foreign) luxury brands," Nakamura concedes.

So which does he find a bigger challenge - the freedom of jazz or the structure of classical music?

"It's a different type of difficulty," says Nakamura, who occasionally performs in small jazz clubs but also plays classical music.

"In either case, it's a competition."

The Geneva auto show is open to the public until March 16.