An "outside" designer has been hired by Smart USA to work up a real-world version of this concept 4-seater due out by 2012.

Struggling to overcome cripplingly slow sales, Smart USA has brought in an outside design house to work on the new small car the maker is developing with help from Nissan.

Jill Lajdziak, smart USA president, confirmed to TheDetroitBureau.com that Penske Automotive Group, has turned to an outside design partner to work with Nissan on both the exterior and interior design for a four-seat Smart.

Lajdziak declined to identify the designer but confirmed the project is already well along.

The project is particularly unusual because Smart USA is working directly with Nissan on the vehicle, without the participation of the smaller maker’s German parent, Daimler AG.

The 4-seater coming from Smart USA-Nissan is expected to be ready for the market by the end of 2011 or in early 2012, at the earliest.

As a one-vehicle line, Smart USA has been hurt by declining interest in the its little fortwo model, which is now more than a decade old. The Smart 2-seater has become a design icon but critics have stated that Daimler AG has let it get stale technologically.

Complicating matters, it is running up against some stiff new competition, such as the Fiat 500, which the Italian maker and its American partner, Chrysler, will begin importing next month.  At just over $15,000 base,

Daimler CEO Dieter Zetsche has promised to update the corporate Smart line by adding a new vehicle developed with help from Renault, and a battery-electric vehicle, the SmartED, which includes batteries from Tesla, is just beginning field testing in the U.S..

Meanwhile, the Penske Group,, Daimler’s partner in the USA, has gone to Nissan for another small vehicle that can help Smart retain its grip on customers in the U.S.