[C/Fe] relation with age. Upper panel: [C/Fe] ratios as a function of age for the full sample. The red line is a weighted (by uncertainties) linear fit to the thin-disk stars to guide the eye on the general behaviour of the trend. The thick purpleline is a weighted fit with a third-order polynomial for all the stars. The dashed lines are the Kobayashi models also depicted in Fig. 3. Lower panel: [C/Fe] as a function of [Fe/H] with ages in colour scale.