  We analyse the dynamical evolution of a fluid with non-linear drag, for which
binary collisions are elastic, described at the kinetic level by the
Enskog-Fokker-Planck equation. This model system, rooted in the theory of
non-linear Brownian motion, displays a really complex behaviour when quenched
to low temperatures. Its glassy response is controlled by a long-lived
non-equilibrium state, independent of the degree of non-linearity and also of
the Brownian-Brownian collisions rate. The latter property entails that this
behaviour persists in the collisionless case, where the fluid is described by
the non-linear Fokker-Planck equation. The observed response, which includes
non-exponential, algebraic, relaxation and strong memory effects, presents
scaling properties: the time evolution of the temperature -- for both
relaxation and memory effects -- falls onto a master curve, regardless of the
details of the experiment. To account for the observed behaviour in
simulations, it is necessary to develop an extended Sonine approximation for
the kinetic equation -- which considers not only the fourth cumulant but also
the sixth one.
