Validation of Vehicle Fuel Consumption - Literature review Example

The global average vehicle fuel consumption hovers around 8L/100 km corresponding to 29.4 mpg and a global drive under the aegis of GFEI, whose partner organizations are the UNEP, IEA, ITF, ITCC, and the FIA Foundation has been launched to bring it down to 4L/100km corresponding to 58.8 mpg by 2050(GFEI,n.d.).The regulations regarding fuel economy followed by the four largest automobile markets, namely, the US, the EU, Japan, and China differ significantly from each other(An et al,2011,p4).

The factors affecting The fuel Economy of a vehicle The seven parameters enumerated by Hilliard&Springer(1984,p9) as influencing the fuel consumption of any vehicle are Engine Characteristics, Drive-train Characteristics, Weight, Aerodynamics, Rolling Resistance, Driving Cycle, and Driver Habits. The various forces which resist the movement of the vehicle are shown as a function of vehicle speed in Fig.2.1(Hilliard&Springer,1984,p8). Fig 2.1 forces resisting the movement of the vehicle as a function of vehicle speed (Hilliard and Springer,1984,p8) In this figure, the rolling resistance appearing at the time-road interface is shown as Curve A and is almost independent of speed.

The aerodynamic resistance is shown as Curve B and it is proportional to the square of velocity. Curve C which is the sum of Curve A and Curve B is defined as the road load resistance and it represents the total force necessary for maintaining a steady speed on an even road. The product of the eight vehicles with the sine of the slope of the road is the grade-resistant force, different values of which, correspond to different values of inclination, as shown in the figure under discussion.

The percent slope, called grade is the tangent of the road grade angle. A schematic representation of the tractive force which is generated at the rear wheels of an internal combustion engine-powered vehicle with a three-speed standard shift transmission is also shown in the above diagram. When the transmission is changed to a higher gear, there is a decrease in speed reduction ratio and a consequent decrease in transmission output torque and hence the tractive force also comes down. The force available for driving the vehicle forward is the difference between the tractive force and the road load resistance and is called the free-tractive effort.

According to Hilliard & Springer(1984,p9), the combinationfree-tractivee resistance forces along with the combined performance of the engine and power drive train gives the ultimate fuel economy potential of an IC engine-powered vehicle while the total of the resistance forces at any operating point has to match the tractive force delivered by the drive train. The aerodynamic drag or the air drag of an automobile is decided by the shape of the vehicle and its frontal area and is proportional to the square of its speed.