Simplify the following text for a Grade 5 native English-speaking person.
Original: On 19 October 2006 , it was announced that Robert Kubica would partner Nick Heidfeld for the 2007 Formula One season with Sebastian Vettel taking the test and reserve driver role .
Simplified: For the season Kubica and Heidfeld were again the teams ' drivers . Sebastian Vettel would be the third or test driver .