The move is one of the final steps in getting the vehicle to dealerships next spring. Certification of the vehicle was recently completed at the company's testing laboratories in Allen Park, Mich.
Ford said the Fusion Hybrid tops the mileage of Toyota's Camry hybrid -- its main competitor-- by 8 mpg in the city and 2 mpg on the highway.
The Fusion can travel up to 47 miles per hour using only battery power. After that, the car's four-cylinder engine turns on to power the car and recharge the battery.
The Fusion's nickel-metal hydride battery is lighter and produces 20 percent more power than the Ford Escape hybrid. It also devised a way to get 28 percent more power out of the battery cells, said Praveen Cherian, program leader for the Fusion Hybrid.
"It's not just one thing, but thousands," he said of the improved mileage numbers.
The battery can also tolerate higher temperatures, and Ford has eliminated its battery cooling system in the Fusion, allowing the battery to cool using regular cabin air.
The company has also improved its regenerative braking system, which captures energy lost through brake friction and stores it for battery usage. Ford said 94 percent of brake friction energy is recovered in the new model.
The Fusion also includes SmartGauge technology, which helps drivers adjust their driving to increase mileage.