I am not sure where such explaination is discribed.
Unless there is a dictionary for Junior Executive Creeps I don't think there is an actual difference in "Bimmer" & "Beamer". I owned two 5 series BMWs in the mid 80s (First one was replaced due to a transmission fault) Back when they weren't so much like "Belly Button Cars". You know, everybody has one. That is mostly aimed at the 3 series, you know BMW Wanna Bs.
My question was in jest NOT AN ACTUAL QUESTION though I never expected a clarification.
Thanks anyway,
Montana