Check to be sure that acceleration continues while the switch is held, and that after it is released the constant speed at the time when it was released becomes the driving speed.
NOTE:
Acceleration can be continued even if the vehicle speed has passed the high-speed limit*. But the speed when the auto-cruise control switch is released will be recorded as the high-speed limit*.
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
NOTE:
* 2.4L Engine: Approximately 170 km/h (106 mph); 3.8L Engine: Approximately 195 km/h (121 mph)