The F21 is the three-door of the second-generation 1 Series, built from 2012 to 2019. It always sold in smaller numbers than the F20 and died at the generation change without a replacement — the F40 came as a five-door only.
At the front it is an F20: bonnet, wings, headlights and bumper are the same parts, including the hard 2015 LCI break where BMW redrew the entire nose. A post-facelift headlight in a pre-facelift wing does not make a fit, it makes a gap.
From the A-pillar back it goes its own way, and more sharply than most three-door/five-door pairs: the doors are longer, the rear quarters cut differently, the window line runs differently. An F20 door will not fit. Inside, though, the two are largely the same car; only the door trim follows the body.
Three-door panels were never plentiful, and what reaches us is mostly condensers, aerials and interior parts.
