INFORMATION PROCESSING SYSTEM AND INFORMATION PROCESSING DEVICE

An information processing system which includes a center server and a movable body performing a communication with the center server, includes a fuel efficiency information obtainment unit which obtains information on fuel efficiency when the movable body moves in a first direction heading toward the other direction from one direction in a predetermined section and obtains information on fuel efficiency when the movable body moves in a second direction heading toward one direction from the other direction in the section; a comparison unit which compares the fuel efficiency in the first direction with the fuel efficiency in the second direction; and a slope estimation unit which estimates a slope of the section based on a difference between the fuel efficiency in the first direction and the fuel efficiency in the second direction.