If true, BMW Blog says that a 4 Series could be offered as a four-door coupe that would help BMW compete with offerings like the A5 Sportback. The move would also enable BMW to offer a more stylish car that slots well below the 6 Series in price while still demanding a premium over the 3 Series. And keep in mind that BMW has already green-lit the 6 Series Gran Coupe, which will feature two-door styling and four physical doors when it arrives in 2012.
Given that Audi has feverishly expanded its lineup the past few years, we wouldn't blame BMW for countering with a 4 Series, but this is the first we've heard of it, so we'll keep this one squarely in the rumormill category for now.