This is true. I've been babysitting mom's Maverick for the last year and I've probably driven it no more than 200 miles in that time. It was around 50% when she dropped it off almost a year ago. Yesterday I looked and it is at 18% and starting to tell me to plan for an oil change soon in the Fordpass App.My wife has a Fusion with an Ecoboost engine and based on my anecdotal exposure, it's not just a mileage counter. I have read - stories from people where it happens to them - that it will track time, i.e. 12 months/1 year, in cases where the vehicle gets driven very little. It will trend to 0% very quickly when it approaches 1 year interval.
I was originally one of the doubters about the time thing, but it appears to be true.
I should have paid closer attention to mine when we took our Disney trip with the camper. Chewing through gas at 9mpg should have dropped the monitor down more than usual, but I didn't give it much mind when we took the trip.