Nicely argued, but I'm afraid it's not quite so simple.
This isn't really a new sort of conundrum; we've faced similar numerous times previously when there have been other variants which may or may not be better off with their own section. The simple fact of the matter is that pending a revolution in the way [technically speaking] forums can be organised - there are awkward choices to be made when it comes to grouping discussion topics.
As you've sort-of identified, these choices all come down to how one differentiates between similar variants. It helps make your point, but I don't think the comparison between petrol/diesel is very valid.
It can be said that the A3 e-tron is at the end of the day, an A3; and as such will have a lot in common with petrol & diesel powered A3s. But it is an e-tron, and that in itself is a new & significant topic, with plenty of discussion points which are irrelevant to those driving internal combustion only variants.
As you suggest, we could split on petrol & diesel. I suppose it's no more or less arbitrary than keeping A3 and A4 separate. Equally though, we could split on red cars and blue cars - at the end of the day, they're different; I'd agree not significantly, but if you don't like red cars...
So, we have to split based on what we think are the most pertinent points. We feel that e-tron is a pretty big deal - it's a new technology which introduces all kinds of new discussions, and the A3 e-tron is the first production model in what will ultimately become a range of next generation types. I suppose to borrow your example, what I'm saying is that is that if this were the first production Audi with TDI (or quattro, or...) it'd probably have its own section too.
Playing devil's advocate for a second... If I removed the 'A3 Sportback' part from the section's title, I guess you'd agree it might be a good place for discussions about economy/efficiency, company car tax, availability of fast charge points, technical matters specific to electric vehicles and business in general related to these new fangled electricty-burners. That's really what we want to provide; it's labelled A3 e-tron because at the moment that's the only one, but in time there'll be A4 e-tron and a host of other e/g/h-tron variants; at which point the silhouette based distinction becomes most relevant again.
Again, we understand that there'll be overlap - it's not ideal, but is also nothing new. Does an RS3 owner with a question about some item of interior equipment (RNS/MMI for example) post in RS3, or in A3/S3? Unfortunately in those cases it's down to the individual to make the choice of which is the more relevant section. Happily though, should individual discussions (or indeed whole sections) begin to look like they'd be better placed elsewhere, we can always move things about.
Anyway, hope that helps everyone better understand the difficulties we face in organising sections, and reassures you that the issues related to it are things we do give serious thought.
All the best,
Rob.
