Auto Start / Stop
An intriguing feature on many of our new models is the Auto Start-Stop feature. It is a simple way to reduce CO2 and fuel consumption during city driving.
When you brake and come to a complete stop, the engine stops but once you take your foot off the brake pedal there is no delay and the vehicle seamlessly starts and moves the car just as if it had never shut off. The process of shutting down and starting up had no effect on the driving experience. On vehicles equipped with this feature, it is automatically on but can be shut off with the push of a button on the instrument panel (it was right below the radio in the Ford Fusion I was driving).
One thing I did find out is the vehicle is programmed not to shut down even if the feature is turned on if the battery charge goes below a certain level (like if the air conditioning or rear defrost is on). The neat thing is when the engine is off it is not consuming gas or emitting exhaust, but the vehicle is programmed to keep the cabin temperature steady for comfort. A light on the dash will let you know when the system is on and you can track its status in the driver information center which can help you maximize your fuel economy. The more in-town (city) driving you do, the more this feature will help save your gas. If you do a lot of that type of driving it may be worth taking a look at the next time you're ready to update your vehicle.
Source: Birdnow Blog