Sirius XM CEO Mel Karmazin tells the Citi conference in San Francisco that in order to make the announced full-year guidance of 1.6 million net new subscribers, they needed to have a very strong fourth quarter. Today the company announces that it signed 540,000 new net subscribers in Q4. Karmazin says the subscriber numbers are "higher than anyone's expectations, and higher than any year since we completed the merger" of Sirius and XM, in 2008. The driver was, literally cars: OEM placement of satellite radio equipment in new cars being sold. Karmazin says although the used car business is smaller, they see improvements there, as well. Sirius XM will officially announce its fourth quarter and full-year results when it reports to Wall Street in February. Sirius XM now has nearly 21.9 million subscribers, and about $3 billion in annual revenue.