I have a 2010 Fusion Hybrid purchased new, and had been getting reasonably good MPG since we purchased it (we love the car). It now has about 68,000 miles. I live in a northern climate (southern Wisconsin), but have been averaging about 40 mpg overall, a little higher in summer and a bit lower (upper 30's MPG) in winter. To the best of my knowledge, my driving habits have remained the same, and we almost always get gas from the same gas station. The car is regularly taken into the Ford dealer where I purchased it for oil changes (and routine checkups) and the recommended checkups at 10K mile intervals.
A couple months ago, my average MPG dropped suddenly and markedly to about 25-26 MPG, and it has stayed in that range. It is indeed winter here, but I have never had this low an MPG on this car even in the winter.
Before I take it into the repair shop, can folks give me some idea what might be happening?