Question on why BMW names their cars the way they do?

I have recently taken a great intrest in these cars. I understand the series categorys but don't under the numbering. Like in the 3 series the cars are 325i to 330xi. Does anybody know what the numbering and the letters?:screwy:

The first number is the chassis, the second two designate which engine the car has.

For example-
With a 2002 325i, the "3" refers to the series (as in 3-Series, 5-Series, 6-Series, 7-Series) and the last numbers refer to the displacement of the engine, a 2.5l.

This system applies pretty accurately to all of the major BMWs, but the displacement can sometimes be off. For example- the 545i had a 4.4l and the 550i has a 4.8l. The newest generation of 3-series is the most confusing because both the 325i and the 330i (as well as the upcoming 335i) have 3.0l engines, the difference between the them is only engine output.

Another way of looking at this is that for a given year, two cars with the same first digit will share a chassis but not necessarily the same engine. Two cars with the same last digits will have the same engine but won't necessarily have the same chassis.

325i and 330i- same chassis, different engine
325i and 525i- different chassis, same engine

I see. Thanks alot for explaining that.