The trend is to increase the production of diesel vehicles owing to the development in the engine efficiency and fuel injection control technologies compared to the gasoline vehicle.
However, the diesel engine exhausts the nitrogen oxides (NOx) and soot at the serious level compared to the gasoline engine. Therefore, to consistently use diesel engine, it is necessary to solve the problem that are fossil fuel depletion and pollution due to the engine emissions.
In particular, vehicles applied to EURO5 had been made since 2011 and emission regulations from engines have become strict to reduce the exhausted gases because of EURO6.
For solving environmental issues of the diesel engine, the control method of the fuel injection process were researched to optimize the structural aspect of the injected fuel.
Some researchers proposed a back-propagation neural network model predicting the exhaust emissions.
Others proposed the fuel design by using change in the fuel composition or uses the additive.
The purpose of the fuel design method is to improve the combustion efficiency and exhaust characteristics by improving the fuel feature with the additive to upgrade the fuel character or using the alternative fuel because the fuel character affects the diesel engine performance and emissions.
Reference:  Yeom J K , Jung S H , Yoon J H . An experimental study on the application of oxygenated fuel to diesel engines[J]. Fuel, 2019, 248:262-277.