BMW Developing 4 Series Four-door Coupe: Report

BMW's line-up may be set to grow even larger in the near future, as reports out of Europe this week point to the possible debut of a four-door coupe dubbed the 4 Series. 

According to reports in the German press this week, the rumoured 4 Series would squeeze in between the existing 3 and 5 Series models, where it would do battle with Audi's own four-door coupe, the A5 Sportback.

Details on the model's styling remain unclear, but if indeed it exists, it could draw inspiration from the Concept Gran Coupe that spawned the new 6 Series coupe.

It could also - and perhaps more likely - be the production name of the coming 3 Series GT, itself a smaller take on the high-riding 5 Series GT.

For now, the existence of the 4 Series looks to be little more than speculation built on BMW's penchant for creating its own segments. If something is coming however, we could hear more at September's Frankfurt Motor Show, where the all-new 3 Series is expected to be revealed.