The energy crisis of the mid-1970's released a frantic search for alternative fuels. The present paper reviews the studies undertaken by the Author's Company and outlines experience with broad specification fuels, vegetable oils and alcohols. Tests were undertaken mainly with the diesel engine and its derivatives in mind.It is concluded that, in the medium term, the most effective engine/fuel combination is an injected stratified charge engine burning “wide-cut” fuel oils. Such oil could be obtained by a modification to present natural crude refining practices, or from shale and tar sand distillation, or by coal gasification and hydrogenation, or from oil bearing vegetation. Unfortunately, the energy scene is currently confused by the conflict between short term economic gain and long term conservation needs. As a result attention is being focussed on gasolene-like alternatives, notably methyl and ethyl alcohol.As a consequence it is thought that carburetted stratified charge engines, burning alcohol-based or alcohol extended fuels, are likely to become dominant in the mobile prime mover field. It is to be hoped that progressive depletion of natural crudes will promote the gradual introduction of a more efficient combination based on an injected stratified charge engine. In any case, eventual shortages of natural fuels will have far reaching implications on the choice of materials for both engine and vehicle manufacture. Government legislation and taxation policies will also be affected.