user: Question: Which class had a vehicle of Nissan in 2007?
Columns: ['Year', 'Class', 'Vehicle', 'Position', 'Stages won']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [2005.0, 'Cars', 'Mitsubishi', '60', '0']
SQL:

assistant: SELECT "Class" FROM "Table" WHERE "Vehicle" = 'Nissan' AND "Year" = 2007.0;