Microsoft and German engineering giant Siemens are teaming up to build computer systems for cars and trucks.

Under an agreement disclosed Friday, Microsoft and Siemens VDO Automotive will work jointly to develop in-vehicle information, communications, navigational, and entertainment systems.

The companies intend to develop the applications on a base of Microsoft's Windows Automotive and Microsoft Auto software platforms, with the first products expected to roll out in 2009. Among other things, Microsoft and Siemens plan to build interfaces that will allow consumers to connect their portable entertainment devices to automobile video and audio systems.

A number of automakers, including Toyota, Honda, and Volvo are already using Microsoft software to power in-vehicle systems. Microsoft also recently teamed up with Ford to develop Ford Sync, an in-car, voice-activated communications and entertainment system that will debut this fall. Ford Sync will allow drivers to access their mobile phones through voice commands and plug MP3 players into their car stereo.

Systems developed through Microsoft's collaboration with Siemens will be marketed by Siemens VDO, which counts most of the world's major auto manufacturers among its customers.

The deal represents a key victory for Microsoft in the embedded systems market, which has become increasingly penetrated by Linux developers. Siemens executives say the company decided to partner with Microsoft because of the software maker's experience in the consumer entertainment market.

"We will make both current and future multimedia and infotainment solutions, some of which are still under development, available to current generation vehicles," said Siemens board member Helmut Matschi, in a statement.