The OEM Michelins are on the car currently and even though the car computer is climbing some, it has yet to hit 40. . They are my non-Winter set. With OEM rims and Goodyear WRT ICE snow tires (my Winter setup) I'm lucky to get 34 MPG on the current car ... yet I was able to maintain mid-30s with the '15. That's why I think the stop&go feature has somehow caused the MPG to drop.
Last 3 tanks by receipt - were 38.75, 34.30 and 37.60 MPG. The 34.30 was an 8.9 gallon fill whereas the others were 10.9 or better.
ADDED IN: Car just had the 30K servicing done. The '15 had 38600+ on it when I traded that so this car is running about the same monthly mileage my prior FFH was.
That is odd, apparently not all FFH are created equal.