NOVELTY - Liquid fuel composition (I) comprises 0.5-20 vol.% of 4-8C olefins containing 0.02-100 wt.% of bio-carbon, based on the total weight of carbon present in the 4-8C olefins.    USE - The liquid fuel compositions are useful in spark-ignition engine (claimed) and heating appliance.    ADVANTAGE - The liquid fuel compositions: can be produced and handled by the existing infrastructure and/or combustion technologies and thus suitable for existing vehicles tank and/or fuel delivery systems; and allow part of the fossil carbon dioxide emissions to be replaced by sustainable or green carbon dioxide emissions, thus reducing the total emission of fossil carbon dioxide.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a liquid fuel composition (II) comprising: a conventional fuel component; and a biofuel component comprising 0.01-80 wt.% olefins, 0.01-20 wt.% +4C oxygen-containing hydrocarbons, 5-80 wt.% linear or branched paraffins, 0.01-80 wt.% cycloparaffins, and 0.01-80 wt.% aromatics, where the biofuel component comprises 0.02-50 wt.% of bio-carbon, based on the total weight of carbon present in the biofuel component;    (2) a liquid fuel composition (III) comprising a biofuel component derived from a fraction of at least one cracking product produced by catalytic cracking of a biomass source, where the fraction comprises light cycle oil, naphtha products and/or its fractions;    (3) preparing the liquid fuel composition, comprising: contacting a biomass material with a catalytic cracking catalyst at a temperature of more than 400 degrees C in a catalytic cracking reactor to obtain at least one cracked product; fractionating the cracked product to obtain a fraction comprising light cycle oil, naphtha products and/or their fractions; using the obtained fraction as a biofuel component and/or converting the obtained fraction to a biofuel component; and blending the biofuel component with at least one other component to obtain the liquid fuel composition; and    (4) operating an engine, comprising: introducing the liquid fuel composition into a combustion chamber of the engine; and operating the engine.