Development of prediction methodology for CO₂ emissions and fuel economy of light duty vehicle

Fuel economy prediction models usually require vehicle specifications such as a fuel consumption map which are not publicly available. Therefore, the present study proposed a new data analyzing procedure to predict CO₂ emissions and fuel economy using on-road driving data without confidential specifications. Vehicle specifications such as gear ratios and vehicle mass which are provided in a service manual and driving data such as vehicle speed and CO₂ emission were used to develop the prediction model. Instead of the fuel consumption map, linear equations for each gear between wheel power and CO₂ emissions were used to predict CO₂ emissions for various driving modes. Since higher gears exhaust less CO₂ than lower gears (the seventh gear exhausted 24.4% less CO₂ than the first gear), the accuracy of fuel economy prediction was improved by applying the equations for each gear stage. The accuracy of the prediction was verified by comparing it with measurement data. The comparisons showed that the equations for each gear can predict the fuel economy more accurately than one equation representing the entire gear. In worldwide harmonized light vehicles test cycle (WLTC) mode, the former had a maximum error of 6.1%, but the latter showed an error of 17.9%.