Politically incorrect in the US, certainly, but why illegal? There is no nudity, etc.
Ok, I agree, I browsed over it and typed that very fast.
However, there are elements of it with a sexual implication, and showing a child when making such an implication can be seen as encouraging illicit sexual activity. In fact, it even suggests "you are not the first to have engaged in such" Overall, it is a very distasteful ad by BMW, and if they get heat over it, they deserve it. In fact a firing of the marketing team would even be appropriate here. The more I look at it, the more I see a child-like doll face, than I see a woman. It might be my bad eyes, but I can't be the only one who has arrived at this conclusion.
On the contrary, BMW can argue the ambiguity around the statement "you know you're not the first". The question is what exactly did they mean? I think we have a pretty good idea, the cop out would be, well you're not the first to have thought she was beautiful or what not..."