1962 Morris 1100
The 1962 Morris 1100 is large enough to have four doors, though the hood and wheels remain proportionally small.
Image below is a side view from 1962 Morris 1100. The body panels are not as crude or basic as those on the Mini. There's even a subtle character line crease along the side and stamped, raised wheelhouse surrounds, unlike the tacked-on chrome surrounds on the Mini.