Simplify the following text for a Grade 5 native English-speaking person.
Original: He is one of the most successful drivers in the history of the Champ Car World Series , having won four successive championships from 2004 to 2007 .
Simplified: He is one of the most successful drivers in the history of the Champ Car World Series . He won four championships in a row , from 2004 to 2007 .