Left panel: cumulative fraction histogram of ΔRV_max for the C_enh stars (green), log g-controlled comparison sample from APOGEE DR17 (black), and the low-α (orange) and early high-α (pink) sub-samples. The C_enh stars are skewed towards larger ΔRV_max values compared to the control sample. Right panel: RV variability fraction as a function of metallicity for the C_enh (green) and control sample (black). Uncertainties on the RV variability fractions are shown as the shading, and bins where there is a difference of between 2σ and 5σ in RV variability are marked with blue and golden stars, respectively. Both samples demonstrate an anti-correlation with metallicity, but the C_enh stars have consistently larger fractions than the control sample.