Just as BMW debuts the first i3 and i8 sub-brand modes, the rumormill starts to spin with the notion that BMW has plans to introduce new i4 and i5 models based off of the i3. The idea of larger i4 and i5 variants, according to a BMW insider, is being considered. The i4 and i5 should be based on the i3’s architecture with a plug-in electric or range-extended electric drivetrain. Could this be BMW prepping early to meet those 54mpg CAFE standards? Either way, just the idea seems enticing.