  We study a class of inhomogeneous and anisotropic $G_2$ string cosmological
models. In the case of separable $G_2$ models we show that the governing
equations reduce to a system of ordinary differential equations. We focus on a
class of separable $G_2$ M-theory cosmological models, and study their
qualitative behaviour (a class of models with time-reversed dynamics is also
possible). We find that generically these inhomogeneous M-theory cosmologies
evolve from a spatially inhomogeneous and negatively curved model with a
non-trivial form field towards spatially flat and spatially homogeneous
dilaton-moduli-vacuum solutions with trivial form--fields. The late time
behaviour is the same as that of spatially homogeneous models previously
studied. However, the inhomogeneities are not dynamically insignificant at
early times in these models.
