The possibility of studying superstring-inspired ${\mathrm{E}}_{6}$ phenomenology at high energy hadron colliders is investigated. A very simple low energy rank-5 supersymmetric $(N=1)$ model is considered, which consists of three Higgs scalars, ${H}_{i=1,2,3}^{0}$, two charged Higgs bosons, ${H}^{\ifmmode\pm\else\textpm\fi{}}$, one Higgs pseudoscalar, ${P}^{0}$, and an extra vector boson, the ${Z}^{\ensuremath{'}}$. The production of charged heavy lepton pairs ${L}^{+}{L}^{\ensuremath{-}}$ by gluon-gluon fusion and the Drell-Yan mechanism is discussed. For gluon-gluon fusion an enhancement in the parton level cross section is expected due to the heavy (s)fermion loops which couple to the gluons. This mechanism is expected to dominate over the Drell-Yan process for ${L}^{+}{L}^{\ensuremath{-}}$ invariant masses above the ${Z}^{\ensuremath{'}}$ mass.