General Motors Corp. plans to offer XM Satellite Radio Holdings Inc.'s satellite radio service in more than 20 car and truck models in its 2003 lineup next fall, the two companies announced on Sept. 4. The commitment from General Motors signals an expansion of an agreement announced earlier this year in which GM said it would offer XM Satellite as a factory-installed option on 2002 Cadillac DeVilles and Sevilles this fall. GM said it would announce specific models closer to introduction. The announcement comes just two weeks after rival Sirius Satellite Radio Inc. said it signed a deal with BMW of North America LLC to offer its satellite radio service to new car buyers in select BMW 3 series, 5 series, and X5 vehicles. XM Satellite and Sirius aim to provide U.S. listeners with digital-quality radio service via satellite. XM Satellite plans to offer 100 channels for $9.99 a month while Sirius plans to offer the same number of channels for $12.95 a month. The two rivals have been vying for deals with carmakers as a way for satellite radio to gain mass-market acceptance. Satellite radios also will be offered in the replacement market. XM Radio will start its service in two cities on Sept. 12 while Sirius expects to launch its service in the fourth quarter. As previously announced, GM customers who want to subscribe to XM Satellite will have the option to include their monthly subscription fees in their leasing and financing bills, the companies said. General Motors has already said it plans to roll out the satellite radio service across all of its models over the next three years.