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2014 Ford Fusion summer gas mileage

Judging from the number of times the Asheville Citizen Times reruns your columns, are you still writing?
If so, please consider this.
My late-model Ford Fusion consistently gets in the neighborhood of 10% less fuel milage in the summer than the winter. Is this the result of my supplier’s difference in summer-winter gas formulation?

It should be the opposite.Your car should get better gas mileage in the summer.If not,there is something wrong with your car. The use of winter tires, longer engine warm-up periods add-up to lower fuel economy in winter.

While the difference is usually miniscule, my current car–and all of my previous cars–gets better gas mileage in the summer.

Last winter, when the temps dropped into the 15-20 degree range for a few days, my gas mileage decreased by ~6 mpg. Usually, my winter gas mileage is ~2 mpg less than my summer gas mileage.

I get 4-6 less MPG in the winter than in the summer. But this is an AWD Subaru, which has lots of CV joints, lots of differentials, all of which stiffen up in the winter.

One reason why cars get better gas mileage in the Summer is because Summer gas blends are denser and have a higher heating value per gallon. In winter, low boiling point hydrocarbons such as butane and pentane are blended with gas so the cars will start in extreme cold and so engines can run with the choke off sooner for lower emissions. This lowers both the BTU’s per gallon and the pounds per gallon.
In the summer, we get the higher boiling point hydrocarbons which are denser both in pounds per gallon and BTU’s per gallon. The high boiling point prevents vapor lock in extreme summer heat and there are fewer hydrocarbon vapors spewing into the atmosphere when we are filling up the tank.

I think the gas blend has a minor role in gas mileage. I know that we had a weird day this previous January where the temp was 70ºF and I got my normal summer 32 MPG, whereas I had gotten 28 MPG with the same gas, on the same trip, same speed, previous week when the temp was in the 20s.

If you live in a very warm climate where the summers are hot and the winters are mild, it could be that the air conditioner compressor runs more in the summer, but the winters are warm enough that the engine warms up quickly but air conditioning isn’t needed.
Also, are you taking longer trips in the winter than in the summer? That could make a difference. Are you going to a warmer climate for the winter months where the temperature is moderate but returning to a warmer climate condition for the summer?

During the spring and fall my cars city fuel economy is 28 to 30 MPG. During the summer months, temperatures 105 to 110 F i get 26 MPG, when it is that hot the A/C compressor and radiator fan are engaged all the time when driving at low speeds.

My hybrid gets best mpgs spring and fall, lower in summer (ac use) and winter (winter gas plus cold weather).