A lot of 1st generation Ford Fusion Hybrid owners have reported reduced electric vehicle operation after nine or ten years of vehicle operation. Turns out that it was a programming issue with the PCM and BECM. Ford released a technical service bulletin (TSB) 20-2142 and you can bring in your vehicle to have it reprogrammed under warranty for free. I just had the reprogramming done and it completely resolved the issue. The work take about a half hour to complete and it'll run like new again. So if you are having this issue with the vehicle, this is the solution to your problem.