 These cars have very serious powertrain problems. The pre-cat disintegrating over time and the bits and pieces being sucked into the engine, possibly causing engine damage, and causing oil burn. All 02-06 Altimas suffer from the same serious design flaw. For that alone you should avoid this car. Other common problems include butterfly valve screws being sucked into the engine and causing damage, timing chain problems, floor boards rusting through, and rough-shifting transmissions. Despite what the Edmunds review says the car is NOT fun to drive. The powertrain is extremely unrefined and noisy. It also only gets around 20 mpg in the city, which is pathetic for a 4 cylinder.