Does the Engine Auto Start-Stop Save Fuel?
2 Answers
According to the instructions for the auto start-stop function, idling for more than one second can save fuel. In congested road conditions, the auto start-stop function can save up to about 15% of fuel, and even more if the traffic is heavier. Issues brought by start-stop technology: 1. Increased fuel consumption: The auto start-stop technology is mainly used in traffic jams, where the engine is often in a hot state. The engine can typically start at 350 RPM, which is nearly half the idle speed. Assuming there are no other loads besides the engine's internal resistance during startup and the necessary equipment such as the transmission's loss, the fuel consumption will definitely be less than during idle conditions. 2. Frequent starts can cause wear to the engine: The engine's internal lubrication mainly relies on the oil film. Given that the auto start-stop duration is very short, the oil pumped up by the oil pump will not completely drain back, and sufficient oil remains on the friction components. The lubrication of friction components during startup, especially during a hot start at such low RPM and short duration, has no significant adverse effects. The belief that it causes significant engine wear applies to cold starts and high-temperature cold start conditions.
The car I previously drove had an auto start-stop function, and honestly, this feature is particularly useful in city traffic jams. When stopping at a red light, the engine automatically shuts off, avoiding unnecessary fuel consumption during idling. My actual measured fuel consumption was about 7% lower than before, saving me dozens of dollars on gas each month. The operation is very simple—just press the brake pedal a bit deeper to trigger it, and the engine automatically restarts when you start moving. Of course, this feature is useless on highways or in suburban areas; it's most effective in congested urban roads. Over time, the battery can easily deplete, so it's necessary to check it regularly or upgrade to a stronger one; otherwise, it might malfunction in winter. But overall, it helps car owners save fuel and money while also reducing carbon emissions, which is good for the environment. I think it's a smart little design worth recommending to friends who commute daily.
