Vehicle driving device

A vehicle driving device including an engine, the vehicle driving device comprising:

• an electric pump provided in the engine and configured to pump an engine oil;
• an electric heater provided in the engine and configured to heat the engine oil;
• a starter motor provided in the engine and configured to cause an output shaft to perform starting rotation;
• and
• a control system comprising a processor and a memory communicably coupled to each other, the control system being configured to control the electric pump, the electric heater, and the starter motor,
• wherein the control system is configured to execute
• a first step of driving the electric pump before startup of the engine and calculating a first actual viscosity of the engine oil based on a load torque of the electric pump,
• a second step of causing the electric heater to operate by supplying a first energy to the electric heater, driving the electric pump after the electric heater has been caused to operate and before the startup of the engine, and calculating a second actual viscosity of the engine oil based on the load torque of the electric pump,
• a third step of calculating, based on the second actual viscosity of the engine oil and a target viscosity of the engine oil, a second energy to be supplied to the electric heater, and
• a fourth step of causing the electric heater to operate by supplying the second energy to the electric heater and then driving the starter motor to cause the output shaft to perform starting rotation.