Simplify the following text for a Grade 9 native English-speaking person.
Original: Keselowski left JR Motorsports and Phoenix Racing after the 2009 season to drive the full season for the # 12 Dodge in the Sprint Cup Series and the # 29 Dodge in the Nationwide series for Penske Racing in 2010 .
Simplified: Keselowski left JR Motorsports and Phoenix Racing after the 2009 season to drive full time for the # 12 Dodge for Penske Racing in 2010 .