Car Fuel Efficiency-Where Next

A validated model which attributes fuel consumption to 11 components of a vehicle's energy loss, has been applied to investigate the benefits from improvements in design parameters which can reduce fuel use. Sensitivity analysis of a large, family sized car, gives the ranked order of design variables for improving fuel consumption as: vehicle mass, idle fuel rate or engine friction (or both) and rolling resistance for urban driving. Amongst the remaining parameters aerodynamic drag is lowly ranked but, in highway driving, it ranks first along with vehicle mass and rolling resistance, thus indicating that the proportion of urban to highway driving, which will vary from country to country is important. Driving conditions should be optimised along with vehicle design for best energy conservation and greenhouse gas mitigation.