  Expressions for G-dot are considered in a multidimensional model with an
Einstein internal space and a multicomponent perfect fluid. In the case of two
non-zero curvatures without matter, a mechanism for prediction of small G-dot
is suggested. The result is compared with exact
  (1+3+6)-dimensional solutions. A two-component example with two matter
sources (dust + 5-brane) and two Ricci-flat factor spaces is also considered.
