ISG (Idle-Stop-Go)
Unless you idle for more than a minute, you're not really saving gasoline. What's more, there are other issues.
Air conditioning, heater, radio, turn signals,etc, all use electricity, not to mention the current draw of the starter, and that a hot engine recently shut off may be harder to start in some cases. Let's hope you have a massive battery in that car.
The amount of gas saved by not idling 35 seconds at a red light may not be worth the expense of extra battery capability or more frequent replacement. You may actually use more gasoline if you idle for short periods of time.
Saving 10% sounds like a pipe dream. You will save a few drops.
