2015 Ford Fusion Hybrid mpg drop after relocation

My 2015 Fusion Hybrid got 43 mpg when I lived in the San Jose, CA area. As I drove east moving back to my hometown of Milwaukee, the MPG steadily dropped. Now in Wisconsin it gets only about 33 mpg. Can that be due to climate, distance above sea level or what? I get it serviced regularly at a Ford dealer.

Some hybrids–and I don’t know if yours is one of them–get poorer mpg as they age because they lose efficiency. There could also be other reasons like a bad mass air flow sensor. Have you mentioned the issue to a Ford shop?

Are your tires at the proper pressure in the cooler weather?

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There may also be subtle differences in the gasoline “mixtures” between what’s available in CA and WI.

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Thanks to all of you. I just had a 90,000-mile checkup done at my local Ford dealer so I assume the tire pressure was checked.
Robert M

A simple tire gauge will tell if the tires are at the correct pressure ( That number will be on a plaque on your drivers door jamb ) . I check mine at least once a month .

Did you mention to the service adviser that your MPG has dropped ?

Not a safe assumption. Check it yourself at least every month or so, or before a long highway trip. Use the pressures specified on the sticker in the driver’s door jamb.

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Here’s a discussion about that problem in an older Fusion hybrid, and the solution, which worked for my 2011. However, yours (2015) seems too young for the automatic battery use reduction Ford imposes once they get around 9 years old.

San jose is pretty close to sea level, and the center of the U.S. is half a mile high or more, it’s possible the computer wasn’t able to adjust to the difference in air pressure - meaning less air being pulled into the cylinders than normal, meaning less power, pressing the gas pedal a bit more to keep the same speed, and injecting more fuel than is needed to keep the air/fuel mixture the car is designed to keep. And so worse mpg.

But this point is invalid if the car actually could “sense” the lower air pressure and adjust to it, or if the mpg is back to normal in milwaukee - since elevation between milwaukee and san jose is very similar.

All modern cars sense the air density (altitude) very accurately. That’s required to make sure the air-fuel ratio is correct.

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On every hybrid I’ve seen…that is detected and a fault is generated. The efficiency drop is because of the hybrid battery. The hybrid battery is really a series of smaller batteries. One or more of those batteries is weak/bad. The individual battery packs can be replaced instead of replacing the whole battery.