Si IIλ6355 velocities plotted against the pEW ratio of Si II features, colour mapped with x₁ for the normal SNe Ia in our sample. The black dashed line at v_Si = 12 000 km s⁻¹ marks the boundary between HV and NV SNe Ia on the plot. SNe Ia with velocities higher than 12 000 km s⁻¹ are classified as HV SNe Ia, while those below are categorised as NV SNe Ia. The filled and empty black diamond represents the weighted average of HV SNe Ia and NV SNe Ia, respectively.