  We show that, for the scalar field cosmology with exponential potential, the
set of values of the coupling parameter for which the solutions undergo a
transient period of acceleration is much larger than the set discussed in the
literature. The gradual inclusion of ordinary and dark matters results in an
everywhere, but near the origin, smoother and right shifted (along the time
axis) acceleration curve. For the 3-fluid problem, the energy density need not
exhibit a plateau during the acceleration period. Much excess in the dark
matter and/or ordinary matter energy densities would lead the universe to
undergo an eternal deceleration expansion. For the 3-fluid problem with a
single exponential potential we conclude that the Big Bang Nucleosynthesis
constraint is not fulfilled if the universe is to undergo a transient period of
acceleration. The 3-fluid model remains a good approximation for the
description of large scale structures.
