CONSTANT SPEED RUNNING CONTROL METHOD FOR VEHICLE AND CONSTANT SPEED RUNNING CONTROL DEVICE FOR VEHICLE

A vehicle constant speed travel control method, in which a target driving power DP_T is calculated based on the difference between a target vehicle speed VSP_T and a vehicle speed VSP; a target accelerator pedal opening APO_T is set based on the target driving power DP_T; a gear shift stage based on a shift map is set in accordance with the target accelerator pedal opening APO_T and the presence or absence of towing (running resistance); and the gear shift stage is more readily set to a low-speed stage (high gear ratio) during towing (as the running resistance increases), wherein the referenced target accelerator pedal opening APO_T is set differently in accordance with the presence or absence of towing (running resistance), and the target accelerator pedal opening APO_T is set to be smaller during towing (as the running resistance increases) with respect to the same target driving power DP_T.