Tina D.
Getting closer, *but* BMWs are never individually called "E-series", "E series", "M-series" or "M series". When someone says "3-series" they mean any and all of the 5 generations of 3XX's. Also, the whole "series" thing identifies closely with Mercedes marketing, not BMW.
With BMWs (bimmers if you will) we just say the E and a number to identify the body variant (E21, E30, E36, E46, E90, etc.) or we say the M and a number to identify the engine variant (M20, M50, M52, etc.)
But these are all "insider" things. The general unwashed public simply refer to the cars by their model numbers. However, this can get very confusing since BMW insists on re-using model numbers continuously: Compare an E30 325i with an E36 325i with a E46 325i or even an E90 325i. They are all very different cars, built on different generations of chbuttis, and with (mostly) different engines, spanning the past 25 years.
Hence the use of the E#'s...
As an aside, I don't ever remember anyone calling a K-bike a "K-series" but it's been quite some time since I sold my flying-brick.
-Fred W