  We prove that the rank (that is, the minimal size of a generating set) of
lattices in a general connected Lie group is bounded by the co-volume of the
projection of the lattice to the semi-simple part of the group. This was proved
by Gelander for semi-simple Lie groups and by Mostow for solvable Lie groups.
Here we consider the general case, relying on the semi-simple case. In
particular, we extend Mostow's theorem from solvable to amenable groups.
