Not sure if this has already been covered, but what are the main differences ( besides the obvious ) between these engines? From what I can see they look the exact same, how can you tell for sure which is which? Where is the number stamped on the engine? Or is there another quick check? has anyone driven a 320i and a 325i? notice a big difference between the two? I ask because I'm starting to think the engine in my 36 is not actually a 2.5 but a 2l. Cheers for any help.