Impact of Z_progenitor on the SN Ia corrected luminosity (i.e. the Hubble residual). Samples with Z of current host galaxies (Z_cur, host) are also presented with empty stars. The average of 10 000 linear regression results (light red lines) from the LINMIX package is shown with the solid red line. The LINMIX fit with Z_cur, host is indicated with the dashed red line. We split our sample at Z_progenitor = 2.5 (the vertical dashed line), where a gap is shown. The green squares are the weighted means of the HR in the different Z_progenitor group.