An evaporative emission control system for a hybrid vehicle comprises a scrubber containing an activated carbon fiber material selected to adsorb butane and/or pentane isomer vapors in low concentrations in air passing through the scrubber and apparatus for resistive heating of the activated carbon fiber material to help desorb the adsorbed butane and/or pentane isomers during a period when the internal combustion engine is operating for combustion of the desorbed vapor in the engine. The fibers are conductive and heat by resistive heating when electric current is passed through the fibers by the apparatus.