Comparison of the [Fe/H] abundance gradients for the stars in the cold disc, corresponding to the linear regressions of Fig. 11, to available observational estimates. The vertical dashed line indicates the average value of the Auriga sample, for all stars (grey) and stars younger than 1 Gyr (cyan). On the right, we indicate the value of each gradient and its standard error along with the p-value of the fit.