• by Erik Sass  @eriksass1, February 9, 2012

Satellite radio broadcaster Sirius XM saw big growth in 2011 both in its subscription base and its revenues, according to CEO Mel Karmazin, who revealed the satcaster’s fourth-quarter and full-year results this week.

The satcaster garnered 1.7 million new net subscribers in 2011, increasing its total subscription base 8.4% to 21.9 million. The number of new additions in 2011 represents a 21.4% increase from 1.4 million net subscribers added in 2010.

The number of new subscribers added from new vehicle buyers increased, even as the proportion of conversions among new vehicle buyers decreased slightly from 46% to 45%.

Total revenues rose 7% to $3.01 billion in 2011. That makes Sirius XM a rival to Clear Channel Entertainment and Media as the largest radio company in the country, in revenue terms. Unlike Clear Channel, most of its revenues are derived from subscriptions, rather than advertising.

Looking to the future, Sirius XM expects to add about 1.3 million net new subscribers in 2012. Karmazin pointed to new personalized radio and on-demand options for listeners as important strategic moves to fend off competition from rivals like Pandora. However, Karmazin said he still considers terrestrial radio broadcasters to be Sirius XM’s main competition.