North American Int’l Auto ShowDETROIT – “Don’t let big happen to you” advertisements for BMW AG’s Mini Cooper used to warn. But after single-handedly creating the premium small-car market in the U.S., “big” is happening to Mini.

On Monday, the auto maker debuted the concept version of a much larger car it says will be on the road within three years. Dubbed the Mini Concept Detroit, the car is modeled after a 4-seat Mini station wagon introduced in 1960 as the Austin Seven Countryman and the Morris Mini Traveller.

That configuration of the original Mini, also called the Mini Clubman Estate, was highly successful and accounted for more than 400,000 sales between 1960 and 1982, BMW says.

This newest version features a much longer wheelbase than the current Mini and a large cargo area. However, company officials say it retains key Mini design cues, such as short overhangs, with all four wheels pushed out to the corners.

Mini Concept Detroit harkens back to the Morris Mini Traveller.

“This is not simply a larger Mini. The vehicle has been redesigned from scratch as numerous details and design elements show,” says Michael Ganal, member of the board of management of BMW AG.

The idea behind the Mini concept is “as small as possible, as large as necessary,” Ganal adds. Mini showed a similar concept vehicle at last September’s Frankfurt auto show. (See related story: Concept Not So Mini)

This latest concept has not been greeted with the same unbridled enthusiasm as when Mini was first introduced, but the brand’s success so far is unassailable.

Mini in 2005 for the first time sold more than 200,000 units globally, and it has sold more than 700,000 units since the 2001 market launch.

The auto maker also had record sales in the U.S. last year, selling 40,800 units, with 60% of those sales higher priced Mini Cooper S models.

Says Ganal: Mini has managed to dispel the perceptions that small cars and hatchbacks do not sell in the U.S. market.”.