A review covering the effect of sulfur on toxicity of the gases exhausted by energy-saving engines, catalyst needs, hydrodesulfurization route and its modifications to low-S (<10 ppm) fuels (e.g., FCC gasoline in the production of gasolines and middle fractions in the production of diesel fuels), and biofuels as components of low-S transport fuels. S-free fuels will remove the technical barrier for introduction of low gasoline consumption vehicles emitting little carbon dioxide. Bioethanol produced from cellulose was indicated as an attractive component of future fuels. Outlooks for developing clean fuels were presented.