i would say very similar ,just vanos units different as most M and non M engines has . but valve stem seals more common on N engines ,very easy to check,leave car to run on idle for few minutes and then acceperatebnegine few times over mid range revs ,blue smoke means valve stem seals gone and dont hold-clean oil from valve ,it gets to combustion chamber and its burned with petrol ,wont really be noticed when car is on the road ,only under heave revving and if somebody is following from the backOriginally Posted by Dave