Engine control method and vehicle traveling control device

A vehicle traveling control device configured to make a vehicle travel by inertia with fuel supply to an engine kept stopped during traveling of the vehicle, the vehicle traveling control device comprising:

• an engine rotational speed detector configured to detect an engine rotational speed;
• an accelerator depression degree detector configured to detect degree of an accelerator depressed by a driver;
• a motor configured to start the engine from a stopped status;
• a fuel injector configured to adjust fuel to be supplied to the engine;
• and
• a controller configured to control the motor and the fuel injector;
• and
• a sensor configured to detect a speed of the vehicle traveling by inertia,
• wherein when no accelerator depression degree is detected, the controller stops fuel supply to the engine, and
• wherein, when the accelerator is depressed after stopping the fuel supply to the engine, the controller prohibits the engine to be restarted until the engine rotational speed drops to or below a predetermined rotational speed threshold, and then, restarts the engine with aid of the motor after the engine rotational speed drops to or below the predetermined rotational speed threshold,
• wherein the controller changes the rotational speed threshold depending on the detected speed, and
• wherein the rotational speed threshold increases with increase in the detected speed.