A process is provided for drawing low-boiling volatile components, such as 2-methylbutane, 2,3-dimethylbutane and pentane, out of fuel in a fuel tank of a passenger car or utility vehicle by applying a vacuum to the fuel tank by means of a diaphragm pump; suctioning off the low-boiling volatile components and condensing the low-boiling volatile components under a pressure that is greater than 1.0 bar. The low-boiling volatile components may be stored in a storage tank and used as engine fuel during cold start of the engine or used as a reducing agent for nitrogen oxides in the exhaust gas from the engine.