  We present a minimal model for the Universe evolution fully extracted from
effective String Theory. By linking this model with a minimal but well
established observational information, we prove that it gives realistic
predictions on early and current energy density and its results are compatible
with General Relativity. Interestingly enough, the predicted current energy
density is found $\Omega = 1$ and in anycase with lower limit $\Omega \geq
{4/9}$. On the other hand, the energy density at the exit of inflationary stage
gives also $\Omega|_{inf}=1$. This result shows an agreement with General
Relativity (spatially flat metric gives critical energy density) within an
unequivalent Non-Einstenian context (string low energy effective equations).
The order of magnitude of the energy density-dilaton coupled term at the
beginning of radiation dominated stage agrees with GUT scale. Without solving
the known problems about higher order corrections and graceful exit of
inflation, we find this model closer to the observational Universe properties
than the current available string cosmology scenarii. At a more fundamental
level, this model is by its construction close to the standard cosmological
evolution, and it is driven selfconsistently by the evolution of the string
equation of state itself. The inflationary String Driven stage is able to reach
an enough amount of inflation, describing a Big Bang like evolution for the
metric.
