In the case of fuel, what is the major difference between BS-IV and BS-VI?

The main difference between BS-IV and BS-VI fuel lies in a sharp cut to sulphur content.

Mercury is not the parameter distinguishing the two fuel standards.

Methane is not the basis of the change from BS-IV to BS-VI.

Carbon content is not what these emission norms chiefly target.

BS-VI slashes fuel sulphur to about a fifth of the BS-IV level, easing emission control.

India moved directly from BS-IV to BS-VI in 2020, skipping BS-V.