It’s typically a three digit number that’s then followed by either 1 or 2 different letters. The first number will represent the series number (the series that the model is). The next two numbers that come in are the ones that will represent the engine displacement in cubic centimeters divided by 100. The more recent BMW models – like the BMW 328i with the OE BMW 328i rims on it – will use the two numbers as a performance index.
Who knew it’d be so complicated to name a car!