Fe II λ5169 velocity evolution for 37 SNe Ic from the sample (see Sect. 6 for the selection criteria). The magenta solid line represents the power law that fits the evolution with time. The blue solid line represents the trend found by Taddia et al. (2018b) and is similar to the one found in this work. The black lines represent the polynomial fit found by Modjaz et al. (2016). As a comparison, we fitted the data also with a polynomial fit, here shown in red.