Holden's Efijy concept car - the star of the 2005 Sydney motor show - is heading to the United States to take centre stage on General Motors' display at next month's Detroit motor show.

The 21st-century hot-rod, which was built by Holden designers in their spare time, is powered by a 6.0-litre V8 that is 11 times more powerful than the original 1953 FJ Holden on which it is loosely based.

It is not destined for production but is being sent to Detroit to display General Motors' global design expertise - and as a bit of a tease.

Holden is in the final stages of negotiating with its US parent company to export the Commodore SS there as a Pontiac sports sedan. A decision is due in the next few months.

The hope is the Efijy will show Americans that Australian car designers have diverse skills, from designing fleet sedans to sports sedans.

Displaying the Efijy at one of the world's biggest motor shows is regarded as a great compliment to Holden's Australian-based design team.

The Efijy would not have been built if it weren't for the designers' efforts and the generosity of suppliers who donated most of the high-tech parts and instruments.

The Efijy is the brainchild of Holden designer Richard Ferlazzo, who had wanted to build a hot-rod-style concept since he first penned one in a moment of inspiration in 1989. "When I started at Holden, when I saw what materials and technology the company had access to, I thought, 'Gee, imagine what sort of a hot-rod you could build with all this high-tech gear,' " he told Drive at the car's unveiling in October 2005.

The Efijy was originally going to be built to commemorate the 50th anniversary of the FJ in 2003 but was delayed by other projects. Its supercharged 6.0-litre HSV engine produces 480kW of power and 775Nm of torque.

The car is based on the stretched and widened underpinnings of a C5 Corvette. "The electrical engineering guys had a Corvette that was about to be scrapped, so we asked if we could use its underpinnings for the show car," Ferlazzo says.

The Efijy is almost as long as a Statesman and as wide as a Hummer and yet has a lower roofline than a Monaro. It can be driven but only at low speeds because the Soprano Purple bodywork is made of fibreglass.

More than 20 suppliers and designers donated time, parts and expertise to build the car over 12 months at a cost of $200,000. However, if it were to be built again from scratch - and if the parts and labour had to be paid for - Holden estimates it would cost $1.5 million.

Inside, the original FJ's humble valve radio has been replaced by a touch-screen display. Buttons on the centre console, which control the four-speed auto transmission, replace the three-on-the-tree gearshift from 1953.

Ferlazzo says the car is all about fun. "It makes people smile. This is a tribute to what can be achieved with today's technology. Imagine what designers could have done in the 1950s if they had today's technology available to them.