BMW is planning to reveal a concept version for its next-generation Z4 at the Los Angeles Auto Show this November, but the current generation of the car is still in dealerships across the country. The final example of the more than 9,300 cars to roll off the assembly line at BMW's Spartanburg plant did so last Thursday, marking the end of U.S. production of the car's current life-cycle.

Production of the upcoming Z4 is expected to return to Germany, and will begin in time for the car to hit the streets in 2009 as a 2010 model. The Spartanburg plant won't go idle, however, as it's expected to pick up with production of the next-generation X3 and the X6, which are stronger sellers in the U.S.

Bobby Hitt, a BMW manufacturing spokesman, told local news source GreenvilleOnline, “It’s been a great car for the plant, [but] in the life of a plant, new models are what drives the energy.”

“It’s exciting to build cars with a strong order bank, that people want,” Hitt said.

The new production at the plant is driving a $750 million expansion, adding a 1.2 million square-foot assembly site and upgrading the paint shop. Already construction of the expanded facilities are underway, with full-scale production expected to begin in 2009.

The next-generation Z4 roadster and coupe are expected to grow in size and performance, with the top-end M Roadster to get as much as 350hp (261kW) from a twin-turbo inline six-cylinder powerplant. Entry level cars will start with just four cylinders in Europe, but all U.S. models are expected to be six-cylinder cars. For more information on the upcoming Z4, plus spy shots of the car in testing, read our story here.