  We introduce the $\ell^1$-ideal intersection property for crossed product
C*-algebras. It is implied by C*-simplicity as well as C*-uniqueness. We show
that topological dynamical systems of arbitrary lattices in connected Lie
groups, arbitrary linear groups over the integers in a number field and
arbitrary virtually polycyclic groups have the $\ell^1$-ideal intersection
property. On the way, we extend previous results on C*-uniqueness of
$\mathrm{L}^1$-groupoid algebras to the general twisted setting.
