DETROIT -- General Motors is developing a new line of minivans with a radically different look in an effort to revive its sales in the segment.

GM will launch at least three new minivans for the 2009 model year on the automaker's Lambda architecture, a platform designed for front-wheel-drive and all-wheel-drive minivans and sport wagons.

Current Chevrolet, Saturn and Pontiac minivans, known internally as U vans, will move to the Lambda architecture. GM may not replace the Buick Terraza minivan, supplier and company sources say.

Production will begin in 2008. GM hasn't announced a location. A year later, GM will offer extended-wheelbase versions of its minivans.

GM began building its crossover sport vans - vehicles based on GM's existing minivan architecture but with SUV-like front ends - last year at its Doraville, Ga., plant. GM's Lambda architecture will debut early in 2007 with sport wagons built at a new plant in Lansing, Mich.

Sources say the new minivans will offer fold-flat seating similar to the minivans offered by the Chrysler group, along with a radical, rounded exterior design.

A GM insider says the GM minivans "look like spaceships."

GM could use a minivan sales boost. It sold more than 300,000 minivans a year from 1997 to 2000, but sales have declined steadily ever since. Last year GM sold 157,169 minivans.

Through the first six months of this year, GM sold 87,524 minivans and held 14.8 percent of the minivan market, down from 15.3 percent a year earlier. Through June, segment leader Chrysler sold 226,908 units and held 38.4 percent, up from 34.0 percent.

The Buick Terraza, Chevrolet Uplander, Pontiac Montana SV6 and Saturn Relay are new for the 2005 model year. But GM hasn't gained any ground with the new minivans.

GM uses the term "architecture" to signify a common set of components, performance characteristics, a common manufacturing process, a range of dimensions and connecting points for key component systems.

A GM insider says the GM minivans "look like spaceships."