Increased Fuel Economy, Indicated and Brake Thermal Efficiency Demonstrated with Coolant Control: An electric coolant pump has been used for some production engines to improve cooling efficiency and fuel economy during cold start. If coolant temperature can be controlled precisely using an electronically controlled coolant pump, fuel economy can potentially be improved not only during cold start, but also under normal driving conditions. Additionally, the reduction in the variability of combustion chamber wall temperature among the cylinders can potentially reduce cooling loss and allow for an increased compression ratio to improve fuel economy of a multi-cylinder engine. Researchers at Chiba University and Calsonic Kansei, Ltd., observed coolant temperature at various locations in the water jacket of a 1.24-liter, inline four-cylinder, gasoline engine during cold start and under steady-state operation at 2,000 rpm with IMEP of 300 kPa. Experiments were conducted to evaluate the effects of cold start with no coolant pump and cold start with preheated engine oil.