Mazda has created a concept car that uses a USB drive as its ignition key, according to technology website CNET.co.uk.

The USB feature reportedly will be part of the Sassou concept, a small hatchback aimed at the youth market that will be unveiled at this month's Frankfurt motor show.

The report said the Sassou uses a USB 'key' and interface port that will let drivers program and load files onto the car's hard drive but auto industry watchers cautioned that such a feature may take years to show up on showroom floors - or it may never make it that far.

Bluetooth, for example, was discussed as a potential feature in cars for six years before it made it into production, a well known US magazine editor told the website.

He reportedly added that Mazda and other car manufactures who may consider offering the USB key feature will have to work out issues such as security.