I was referring to platform-sharing across vehicles with more differences than 2/4 doors. The poster I quoted stated that the underpinnings of a small car, a medium car, and an SUV were all very similar. While a small car sharing a lot of design characteristics with a small unibody SUV is certainly nothing new (e.g. lift Corolla slightly and put new bodywork on it = Rav4), seeing the same platform (or variations thereof) for cars in multiple segments didn't used to be nearly as commonplace as it is now. I mean, look at somebody like Volvo. Everything they sell with the exception of the XC90 is now on the platform they introduced with the 2004.5 S40. Compact to fullsize. They put a different name on the big platform, but there was no major re-engineering, just mods for a longer, heavier car. I may just not know enough about BMW- maybe there have always been various E-designations at a time with very similar design.