The declared aim of this paper is to explore the possible effects of the need for energy conservation (and in particular the need for economy in the use of oil‐based fuels) on road vehicle development in the UK over the next few decades. In the absence of the author, his colleague, R J Francis, also of Harwell, presented this paper at the conference held by the Institute of Management Services in London, September 1980. He stressed the fact that the views here are those of ETSU, and may not necessarily be regarded in any way as “government policy”. ETSU is the Energy Technology Support Unit, which is based at Harwell, and was established in 1974 to formulate and manage research, development and demonstration programmes in the technology of renewable energy sources and conservation under contract to the Department of Energy. There are approximately 45 professional staff at ETSU (mainly scientists and engineers) working in three main areas: strategic planning of research and development, management of R&D on the renewable energy sources, and research, development and demonstration in energy conservation. When introducing this paper, Richard Francis said that it set out to establish the need for conservation in general, as well as to explain how this is to be achieved in practice. This subject, he commented, leads on to the special task of improving fuel economy and achieving wider fuel flexibility within road transport, which itself has wide implications for road vehicle technology. This paper reviews all the more realistic alternatives, and then attempts to identify those which seem most promising and also to quantify the impact they might have in reducing our dependence on oil‐based fuels.