This depends on the size and type of the engine, mode of driving whether, city or highway, and weather conditions. In addition,increased performance and lower operating temperature of the vehicle will be noted. Molecules that are nonhomogeneous are found in both gasoline and diesel fuel. As these molecules begin to cluster and grow, some molecules become trapped during combustion, air is unable to reach the trapped molecules and they do not burn completely. However they will still be proportionally improved.
Fuel flow is important to the process of breaking up the hydrocarbon chains.
The smaller the engine,the more efficient, the slower the fuel flow. With larger engine it is reversed,thus faster flow and quicker results. This is directly proportional to the amount of driving you do and the price you pay for fuel.