General Motors is to widen the number of vehicles on which it offers XM Satellite Radio as a factory-installed option from 25 in the 2003 model year to 44 for the 2004 model year, more than three-quarters of its entire fleet of cars, trucks, minivans and sport utility vehicles, Reuters reported.

GM and XM did not disclose further financial terms of the joint business, Reuters noted.

GM spokesman Mike Merrick told Reuters that GM customers pay $US325 for equipment and installation plus a monthly subscriber fee of $9.99.

Merrick told Reuters that GM, which aims to increase market share with the technology, wants to offer satellite radio on all of its US models by 2005.

"It's a great entertainment piece," Merrick told Reuters. "We think it's a match across our portfolio line."

Satellite radio, offered by XM and its rival Sirius, offers coast-to-coast listening of mostly commercial-free programmes with a sound quality claimed to be superior to FM. The fledgling services are, however, about to face new competition from digital radio broadcasting which gives car buyers yet another in-car entertainment choice.