By Jorn Madslien BBC News Business reporter at the Frankfurt motor show

The Traveller marks early efforts to extend the Mini brand...

The rebirth of the 1960s Mini traveller seems certain after a warm reception for a concept of the car at the Frankfurt motor show.

"This could be a third Mini," Michael Ganal, member of the management board of Mini's parent BMW Group, tells BBC News in an interview.

Nothing is official yet, but there are strong rumours that the traveller could appear in showrooms in 2007 after an anticipated production start at the Mini factory in Cowley, Oxford, next spring.

But much depends on the response from visitors to the Frankfurt show and from the motoring press, Mr Ganal insists.

A bridge too far

The industry is also abuzz with rumours about a whole string of new Mini models that could include whacky versions such as a stretched Mini 4x4, a sleek coupe, a two-door two-seat version of the BMW's roadsters, or even a Mini pick-up.

... but there are limits to how far it can be stretched

Mr Ganal is loath to confirm such rumours and insists that no long term plans are in place, though he acknowledges that it is the group's philosophy to seek growth by launching derivatives of its existing models.

Some observers fear Mini's image as a cute and sporty car could be damaged by increasingly obscure derivatives, beyond the current One and Convertible models, but the company insists its progress is measured.

"We grow the brand step by step," says Mr Ganal, whose responsibilities include sales and marketing.

Weight and bulk

One model that illustrates the point is the BMW Z4 coupe, which is based on BMW's successful Z4 convertible.

BMW's Z4 coupe will go head to head with Porsche's Cayman

The model comes along with a slew of coupes from other car makers that offer the added advantage of a retractable roof. Volvo's new C70 and Volkswagen's Eos coupe convertible models are both expected to sell well.

Yet, Mr Ganal does not accept that it would have been a better idea to launch a Z4 coupe convertible.

"We are a brand that stands for authentic products," he says, insisting that "retractable hard-tops force you to have a car that is massive at the end".

Such additional weight and bulky rear-ends would not suit a proper roadster which should have a slim, light tail, he explains.

He would, however, consider such cars "if these problems could be overcome".

Crowded market

The Z4 coupe will compete directly with Porsche's Cayman, which also enjoys its premiere in Frankfurt.

The Cayman looks a lot like the much more expensive 911

The Cayman is a derivative of Porsche's convertible Boxster, its cheapest model yet.

The Cayman has been hailed as a pretty decent car with looks that makes it virtually indistinguishable from the Porsche 911 family model, raising questions about the effect it might have on sales of this much more expensive car.

The Z4 and the Cayman are carving out a new market, insists Mr Ganal, acknowledging that DaimlerChrysler and Volkswagen are also about to enter the narrow segment with two-seater versions of their own, the Mercedes SLT - a derivative of the SLK coupe convertible, and the VW CCR.