  The critical behavior of driven lattice gas models has been studied for
decades as a paradigm to explore nonequilibrium phase transitions and critical
phenomena. However, there exists a long-standing controversy in the
universality classes to which they belong. This is of paramount importance as
it implies the question of whether or not a microscopic model and its
mesoscopic field theory may possess different symmetries in nonequilibrium
critical phenomena in contrast to their equilibrium counterparts. Here, we heat
with finite rates two generic models of driven lattice gases across their
respective nonequilibrium critical points into further nonequilibrium
conditions. Employing the theory of finite-time scaling, we are able to
unambiguously discriminate the universality classes between the two models. In
particular, the infinitely driven lattice gas and the randomly driven lattice
gas models belong to different universality classes. These results show that
finite-time scaling is effective even in nonequilibrium phase transitions.
