Method of improving fuel efficiency of fuel cell electric vehicle by using navigation information, and apparatus and system therefor

A fuel cell system controller for controlling a fuel cell system, the fuel cell system controller comprising:

• a communication device configured to collect navigation information and vehicle speed information;
• a calculation device configured to calculate a coasting line when a specified event point is detected based on the navigation information;
• a determination device configured to determine whether deceleration is necessary by comparing a current traveling speed with a coasting line speed corresponding to a current location;
• and
• a change device configured to change a motor torque reference value to a specified level higher than a currently set motor torque reference value when deceleration is necessary;
• wherein the determination device is configured to determine whether to enter a fuel cell stop state by comparing a current motor torque and the changed motor torque reference value.