I drove in ECO my first four years or so in my 2012, starting in November, 2011. A service technician said I could get just as much mileage if I drove without it as long as I used awareness (esp starting at traffic lights).
I used to keep careful track of each trip back then. I did see about the same mileage, though on steeper hills I’d slip into ECO. I replaced my car (totaled in 2021 by someone who made illegal left turn into me) with a low mileage 2019. Gotta love a 62kw battery.
I don’t use epedal, I stay in D and flip to B at will. I use ECO only rarely- usually when I want a very slow start (uphill on a grassy or slippery surface). I don’t enjoy the “governed” feeling I get with ECO, though it was highly useful initially as I learned what instant power felt like.