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The 2013 Ford Fusion will be launched with an optional automatic engine start-stop feature. To realize engine start-stop on a vehicle equipped with a conventional powertrain, there are two major challenges in the vehicle system controls. First, the propulsive torque delivery from a stopped engine has to be fast. The vehicle launch delay has to be minimized such that the corporate vehicle attributes can be met. Second, the fuel economy improvement offered by this technology has to justify the cost associated with it. In pursuing fuel economy, the driver's comfort and convenience should be minimally impacted. To tackle these challenges, a vehicle system control strategy has been developed to accurately interpret the driver's intent, monitor the vehicle subsystem's power demands, schedule engine automatic stop and re-start, and coordinate the fast and smooth torque delivery to the wheels.

A typical pattern of city driving includes many accelerations and decelerations. A significant portion of the fuel energy is spent to accelerate a vehicle. This energy is typically wasted during subsequent decelerations. Capturing and reusing some of this energy would improve fuel economy. At present, it is generally accepted that electric hybrids represent a proven technology capable of capturing and reusing a portion of the braking energy. The major drawback of electric hybrids remains the high initial cost of hybrid drivetrains. An Air-Power-Assist (APA) engine, also known as “air hybrid”, accomplishes the same general type of energy storage and reuse as an electric hybrid but with greater simplicity [1, 2, 3, 4, 5].