Vehicle usage aspect1. ua (given ig)Curve of Q~u,-→ug(EconomyRangeofSpeed)
Curve of Qs~ua →ug（EconomyRange of Speed） 1. ua （given ig） Vehicle usage aspect
Curve of Q~u,（high gear),(L / 100km)Kua=F1u. 小= Pamedd= output power ratio = b个个CFbOsAnT>0. 个Vhigh-low-highug(Economy Range of Speed) u.(km/ h)
Curve of Qs~ua（high gear） /100 ) Q L km （S u (k m/ h) a V ( ) g u Economy Range of Speed b s T a a e needed CFb Q s u F u P Q output power ratio high low high
Curve of Q-u,（high gear)0,(L /100km)ua个=Pe-neded个个,F个个O-CFbH01output power ratio个L6+或个Vug(Economy Range of Speed) u.(km/ h)
/100 ) Q L km （S u (k m/ h) a V , T a e needed CFb Q s u P F Q b output power ratio 或 Curve of Qs~ua（high gear） ( ) g u Economy Range of Speed
ConclusionThe increase of b caused by much lower output-powerratio is the main factor causing the increase of Q, whenthe vehicle is driven with lowspeed;Although b decreases greatly for the increase of output-power ratio, the tremendous increase of needed power-peis the main factor causing the increase of Q. when vehicleis drivenwithhighspeed;Because of the abovetwo conclusions,Q,could possiblymeet its lowest value when the vehicle is driven with themedium range of speed where b and pe would escapefrom getting theirhigh value, and we call this range asEconomy-RangeofSpeed（经济车速区间）
• The increase of b caused by much lower output-power ratio is the main factor causing the increase of Qs when the vehicle is driven with low speed; • Although b decreases greatly for the increase of outputpower ratio, the tremendous increase of needed power-pe is the main factor causing the increase of Qs when vehicle is driven with high speed; • Because of the above two conclusions, Qs could possibly meet its lowest value when the vehicle is driven with the medium range of speed where b and pe would escape from getting their high value, and we call this range as Economy-Range of Speed （经济车速区间）。 Conclusion
Fuel consumption curve of a carQs(/100km)II'III/IVVVI1ua(km/h)50709011030
Fuel consumption curve of a car