ACC extended mode operation

When employing an a cruise control system in a commercial or heavy-duty vehicle, an adaptive cruise control (ACC) system (14) is activated upon activation of a vehicle or set-speed cruise control (SSCC) system (16). The ACC (14) remains on, even after SSCC shutoff, to maintain a minimum following distance for a primary vehicle in which the ACC (14) is employed and a forward vehicle. The ACC (14) is deactivated after detection of an ACC shutoff trigger event, which may be driver application of the brakes of the primary vehicle, driver-initiated acceleration for a predefined time period, expiration of a predetermined time period, manual shutoff (e.g., via a switch or button), etc.