See also:

Low speed automatic cancellation
ACC is not functional at vehicle speeds below 16 mph (26 km/h). Once the vehicle speed drops below 16 mph (26 km/h), an audible alarm will sound and the automatic braking will be released. ...

Resuming a set speed
Press and release RESUME. This will automatically return the vehicle to the previously set speed. ...

Breaking-in your vehicle
Your vehicle does not need an extensive break-in. Try not to drive continuously at the same speed for the first 1,000 miles (1,600 km) of new vehicle operation. Vary your speed frequently in order ...