Im looking to purchase a E46 possibly coupe, of around 2000 - 2003 registration, however knowing nothing about BMW cars the engine sizes confuse me, so

316 - is it a 1600 or an 1.8?
318 - is apparently a 1.9?
320 - is apparently a 2.0 ?
323 - 2.3?
325 - 2.5
330 - 3.0

apparently the 325 and the 330 are similar engines? Obviously one being more powerful than the other?

Which is the best engine to go for? i was thinking of 323 or 325? 330 would a little juicy and 318 a little underpowered for a german heavy car?

thanks