In stepped transmissions, the layout of the largest gear is decisive since the largest proportion of a vehicle's operating time takes place at this ratio. The corresponding curve should be as close as possible to the point of minimal specific fuel consumption.
If the track fuel consumption for the single transmission levels is applied over the driving speed, the qualitatively presented consumption diagram shown in the figure results. Driving in the highest possible gear can also be considered fuel efficient as depicted in this figure.
In contrast to stepped transmissions, CVTs offer the possibility to freely choose the engine operating points for a prescribed power demand on the lines of constant engine power. Thus the optimum value can be adjusted as per requirement. In this way, using appropriate transmission control, it is possible to transform the demand curve such that the engine always operates in a fuel-efficient range. A deviation from this control line is made only in the upper speed range in order to make an excess torque available up to the nominal point.