Road-holding – also written as roadholding and road holding – (in French being called "tenue de route", in German "Beibehaltung der Spur"), is essentially determined by the ability of a vehicle to stay on the road and on a desired trajectory of motion, whatever the circumstances (in curves, on greasy, wet or low-grip ground, loaded or not, etc.)
[1] (Hereby, the laws of nature as a framework, including the gravitational field of the planet Earth as well as the phenomenon of inertia, are tacitly assumed as given.)
In the above context, the straight-line stability of a vehicle – which is concomitant with its ability to stay on a desired trajectory of motion – necessitates a certain degree of understeering.
To improve comfort in this regard means, basically, to limit the vertical acceleration fluctuations of the vehicle body and hence of passengers.
[6] For vehicle speeds above approximately 40 meters per second, the effects of aerodynamic forces at an automobile (that is not designed in a too odd manner) tend to become sensible for its road-holding.