Yes, I am having the same issue, 2017Infiniti QX60, at one point from Dec 17-Feb 18, we were only averaging11.9 miles per gallon and when the temperature started going up, mileageincreased to 13.7, beginning of April it became 15.9 and with over 60 degree outsidewe get about 18 something per gallon on local drive. We were fine at the firstthree months averaging about 20 something around city and highway. But itstarted going down since the Dec 2017, then I started noticing that when it'slow temperature outside, the transmission acts up weird, it get stuck on 4thspeed on 35 miles and the engine RPM stays at above 2000. I complained this tothe dealership I purchased the vehicle, plus another dealership closer to me.Both of them tells me that there is no error code, also the service manager inClarendon Hills keep saying that the low gas mileage is due to the gas mix withOxygenates. I understand that you lose 3-4 mile but not 10 miles. My BMW 535XI,still get the almost same mileage in winter and summer. One time I test drovethe vehicle with a technical, showed him how it acts up in cold temperature.They keep telling me this is how the CVT transmission works, I think that isfull of crap. Both dealers, they have the worst customer service (sameowner), once they sell the vehicle to you, their behavior changes. Ireally regret getting this brand new vehicle. My old Lexus GX470 was getting 14miles regardless if winter/summer.