  Self-consistent treatment of cosmological structure formation and expansion
within the context of classical general relativity may lead to "extra"
expansion above that expected in a structureless universe. We argue that in
comparison to an early-epoch, extrapolated Einstein-de Sitter model, about
10-15% "extra" expansion is sufficient at the present to render superfluous the
"dark energy" 68% contribution to the energy density budget, and that this is
observationally realistic.
