Nissan Altima sedans equipped with 4-cylinder engines have qualified for Partial Zero Emissions Vehicle (PZEV) certification in the 2004 model year. The Altima joins its Sentra stable mate in attaining this stringent emissions certification. Achieving PZEV status reduced the Altimas horsepower slightly from 175 to 170. The Altima PZEV will be sold in California and Northeastern states.