The energy - efficient two - phase driving cycle (eta n greather than 1) can efficiency eta n in vehicles be higher than 1.0 ?

The study presents an important part of fourth chapter of the monograph 'Energy Consumption in Relation to Fuel Efficiency Under Complex Driving Conditions' (2003) concerning opportunities to improve vehicle drive efficiency through application, during one phase of driving in neutral in two-phase driving cycle. Theoretical simulation of total energy consumption in vehicles with SI engine provided explanation of a relatively low fuel efficiency observed under real driving conditions in serial cars [1]. The study cites the original method of calculations developed by the author in order to calculate the efficiency of vehicle power unit in two-phase driving cycle assuming that one of the phases might be non-driving. The calculations were made for complex driving conditions, i.e. simulated changes with predefined steps for road slope (-3.5o to 3.5o), acceleration (-0.36-0.36 m/s2) and average speed (60-140 kmph) for a distance of 2x500 m. The results of calculation variants for each type of a drive system of a car proved that there are significant limitations of optimising the fuel consumption of cars. The first one is conditioned by the fact that the engine works at full dynamic load and the second one by the fact that idle running is against the 'Highway Code'.