[en] Fusion excitation functions for the systems ⁴⁰Ar+sup(112,116,122)Sn and ⁴⁰Ar+sup(144,148,154)Sm have been determined, covering cross sections ranging from several hundred mb down to the μb level. The data show a pronounced correlation of the subbarrier behaviour with low-energy collective properties of the nuclei involved and are well reproduced by simplified coupled-channel calculations coupling fusion to inelastic channels. The possibilities of parameterizing the data in terms of a simple dynamic barrier-fluctuation phenomenon are discussed and result in the prediction of remarkably diffuse partial-wave distributions above the barrier. This is shown to be important for the analysis of deexcitation phenomena following fusion reactions. (orig.)