PURPOSE: To indicate the state of fuel consumption of a vehicle accurately by using accelerator sensor signal during ordinary running and rack signal during auto-cruising alternately as an engine load signal according to the occasion.

CONSTITUTION: During ordinary running, both signals from an acceleration sensor 6 and an engine revolution sensor 5 are given to an indicator 8 for indicating fuel consumption. On the other hand, during auto-cruising operation, a main switch 11 is operated, followed by operation of a set switch 12 for setting car speed and a pilot lamp 10 indicating auto-cruising state is lighted. As a result, the decrease of the potential of a point P acts on a relay R and changes over a contact S, giving the rack signal through a terminal T to the indicator 8. The indicator 8 computes the fuel consumption and indicates whether it is good or bad in color according to the signal from a rack sensor 3 and the output from the sensor 5.