I have been experiencing a sharp drop in mpg from 52 to 42 (comparing to same time of the year in the past) . It did start right around the time I got my factory tires replaced with Michelin Defender at least 18 month ago (and 25000+ miles later). Alignment checks out, and I do 40/38 PSI just like I did with the stock tires. What could be the cause? A few things I notice is - My commute has not changed for years and the 10 mile one way trip now gets me 42 mpg instead of 52+ - On long trips (those over 60 miles), I am still able to get 50+ mpg sometimes - Car has a hard time (doesn't want to) go into EV even after driving it for 20 minutes in the summer. Several times (when no one was behind me) I just let go break at a stop sign and the car would go 6 mph for an entire block with ICE on.
I run AC when it get warm outside like above 80 degree. Only in the summer time and probably I don't run AC any more than past years.
Not sure what you mean by thrown any codes. I never asked the dealer to look into this issue. I never cleaned the fan but I do notice it come on very rarely - I mean the frequency of it been on and the speed (judging by the noise it generate) has not changed since I got the car.
Heat, indeed. A/C usage results in a pretty significant MPG drop. That, along with the added weight (19LBs apiece) of the Michelin tyre, can also affect the mileage. You just have to be more frugal with the throttle and braking to make up for some of the loss.
Did an oil change recently? The oil level can cause less mpg. Also, have u done the transmission fluid drain and refill?
