Start-stop system

In automobiles, a start-stop system or stop-start system automatically shuts down and restarts the internal combustion engine to reduce the amount of time the engine spends idling, thereby reducing fuel consumption and emissions. This is most advantageous for vehicles which spend significant amounts of time waiting at traffic lights or frequently come to a stop in traffic jams. This feature is present in hybrid electric vehicles, but has also appeared in vehicles which lack a hybrid electric powertrain. For non-electric vehicles (called micro-hybrids,) fuel economy gains from this technology are typically in the range of 5 to 10 percent.

On a manual transmission vehicle, stop-start is activated as follows: Stop car & press clutch - move gear lever to neutral - release clutch - then the engine stops. The engine won't stop if the car is moving, even if the aforementioned steps are followed. The engine restarts when the clutch is pressed prior to selecting a gear to move the car. The engine may also restart if there is a demand for power from, for example, the AC system.