Sirius Satellite Radio on Monday said it has extended to 2012 its exclusive contract with DaimlerChrysler, which has agreed to factory-install Sirius radios in Chrysler and Mecedes-Benz vehicles and Freightliner trucks.

For the model year 2006, the Chrysler Group alone is expected to generate more than 750,000 Sirius subscribers, the New York-based digital-radio service said.

"Our relationship with Sirius has been a 'win-win' for both companies, as the popularity of satellite radio continues to grow," Robert Schott, vice president worldwide procurement and supplier strategy for the Chrysler Group, said in a joint statement with Sirius.

The DaimlerChrysler deal has been extended to Sept. 1, 2012.

In the third quarter, Sirius added 359,000 net subscribers for a total of more than 2.17 million. The company expects to end the year with 3 million subscribers.

In driving subscriptions, the company is focused on deals with automakers to factory-install its services, and on launching exclusive programming, such as shock jock Howard Stern in January and Nascar coverage in 2007.

Sirius, however, has about half of the subscribers of its chief rival XM Satellite Radio Holdings Inc., which expects to end the year with more than 6 million customers.

Like Sirius, XM, based in Washington, D.C., is driving growth through deals with carmakers and exclusive programming, such as Major League Baseball coverage that started this year. Among the automakers that have agreed to factory-install XM radios include General Motors, Honda, Toyota and Hyundai.