Originally Posted by Enduro
Audi's move to splitting the A4 to sedans (A/S/RS 4) and coupes (A/S/RS 5) and BMW following suit with dividing the 3-series is what I meant here.
My statement in not being able to distinguish between 3er, 5er, and 7er was aimed at cars from the same generation (E65, E60, E9x), not between designs. The different Bangle designed models for instance, were clearly different from each other with respect to overall body lines. The current line-up of sedans (F01, F10, F30) have very similar body lines (at least to my eye), which perpetuates the small, medium, large concept. That said, Audi has worked with this idea with their A/S 4, 6, and 8. One car, three sizes.
Just my 0.02
That's why I chose pictures of 1970ies BMW models. There is a clear design philosophy and similarity between the 3/5/7 series even back then, nothing new in that (IMHO).