for the E46, the 318i comes in either the M4TUB19 which is 1.9 liter or the N42B20 which is 2.0 liter...
not sure what the reg card says but it should be 1.9 or 2.0
As for the E39 523i, it's actually a 2.5 liter engine...
Same thing with some of the merc engines, badged as C/E200 but actually 1.8 liter engine...