I have a 2010 Fusion hybrid. It has an excellent Aisin transmission. In 2013, Ford started building hybrid transmissions inhouse and had issues with them for at least two years (Toyota had trans issues with their first two years of hybrid trans also). This makes me Leary of buying a first...
You should be getting better mileage on your fusion. There is a reason it has gotten worse. https://www.fordfusionforum.com/index.php?app=forums&module=forums&controller=topic&id=19361