(Adds details, compares with analyst estimates; adds share movement)
April 28 (Reuters) - Sirius XM Holdings Inc raised its revenue and subscriber additions forecast for 2015 as strong U.S. auto sales drive an increase in customers for the satellite radio service.
People who buy new cars fitted with Sirius receivers usually get free access for a few months, but must pay a fee to continue the service.
The number of Sirius's paying subscribers rose 7.4 percent to 27.7 million as of March 31 from a year earlier - the highest rate of increase in six quarters.
Auto sales in the United States have been healthy in the first three months of the year, with consumer demand for new vehicles strengthening.
Sirius, which competes with music streaming services such as Pandora Media Inc and Spotify, said it now expects to add 1.4 million net new subscribers this year, up from its prior forecast of 1.2 million.
The company also raised its revenue forecast for the full year by $70 million to $4.47 billion.
Analysts on average were expecting 2015 revenue of $4.49 billion, according to Thomson Reuters I/B/E/S.
Sirius shares were down 0.5 percent in premarket trading.
The company's net income rose to $105.7 million, or 2 cents per share, in the first quarter ended March 31, from $94.0 million, or 2 cents per share, a year earlier.
Revenue rose to $1.08 billion from $997.7 million.
Analysts on average had expected a profit of 3 cents per share on revenue of $1.09 billion.
(Reporting by Sai Sachin R and Lehar Maan in Bengaluru; Editing by Joyjeet Das)