Results of controlled simulations of the formation of lopsided bars in MW-like galaxies. Upper panels: evolution of the shape of the interacting MW (left) and the MW with an off-center disk (right). The blue and red lines plot the intermediate to longest b/a and the shortest to longest c/a axis ratios, respectively. The green and black lines show the evolution of the triaxiality parameter T and the bar mode A₂. Lower panels: odd Fourier modes of the stellar component of the interacting MW (left) and the MW with an off-center disk (right) as a function of time. The red, green, blue, and black lines show the results for m = 1, 3, 5, and 7, respectively. In all panels, the vertical gray line indicates the time of bar formation.