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

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... 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.