The Ford Fusion and Mercury Milan sedans will now be available with a hybrid powertrain for the 2010 model year starting in 2009, positioning these mid-size sedans could to become the most fuel efficient cars in the United States. Ford expects its new hybrid sedans to achieve 38 mpg in the city, which is 5 mpg better than its competitor, the Toyota Camry Hybrid.
While the 2.5L engine is shared with the Escape, enhancements have been made to the electrical components. The latest version of the Ford Fusion / Mercury Milan hybrid system is smaller, lighter, more powerful and less expensive in production. While the Ford Fusion / Mercury Milan battery pack still employs nickel-metal hydride batteries, the number of cells has been reduced. The battery pack is 30 percent smaller, weighs 23 percent less, and each cell produces 20 percent more power compared with the Escape Hybrid’s battery pack. In addition, the battery pack no longer needs its own air conditioning system. Instead, cabin air can be routed through the pack to keep it cool.
The reduction in cell count results in a reduction of the nominal system voltage to 270 volts. Ford has reduced the voltage to improve the efficiency of the power electronics. Higher voltage causes more resistance and heat to build up in the switching circuits. Normally, a voltage reduction would mean a corresponding reduction in power for the electric drive system. However, Ford’s engineers have added a variable voltage controller (VVC) to the Fusion / Milan hybrid that allows the voltage from the battery to be stepped up on demand. During most driving conditions, when little power is needed, the lower voltage increases the efficiency of the electric drive system, while the VVC allows even greater output when needed for acceleration or regenerative braking. The battery management system of the Escape was designed by Sanyo Electric Company.
The hardware package for the Fusion / Milan hybrid drive and transmission is similar to the Escape. The power electronics are now integrated in a sealed container mounted directly on top of the transmission. This eliminates some of the external high voltage wiring, easing vehicle assembly and improving reliability.
The components of the hybrid transmission have been reworked, improving the output of the motor / generator. The motor power is now up to 93 kW compared to the 70 kW output of the Escape. With the on-demand voltage increase of the variable voltage controller, the new motor can now drive the Fusion and Milan on electricity alone at speeds up to 47 mph. The system can now support automatic start/stop twice as often.
The Ford Fusion / Mercury Milan will have digital in-dash gauges and displays. One display in particular will be a green vine seen on the right side of the dashboard. The green vine is a data-visualization tool installed to discourage wasteful driving habits such as rapid acceleration and braking. The green vine gauge will lengthen during efficient driving practices and shorten during inefficient handling.