Mileage declining - Why?
 

We have a 2008 Ford Escape Hybrid w/ approximately 8000 miles on it. To date, we are averaging about 35.5 mpg. When I fill the tank, I calculate the mileage of each tank individually and am generally within about a mile or two of that average. My last tank however, I averaged only about 31 mpg. With the exception of cooler weather and using the heat a little more, can anyone think of what would account for such a sharp drop? Earlier in the year when it was cold and we used the heat, we were up around our normal average so this seems odd.

Conditions/routes have been about the same as the previous tanks.

Re: Mileage declining - Why?
 

If the gas station has changed to "winter grade" or higher ethanol content, this could account for the drop in MPG.

Re: Mileage declining - Why?
 

I agree. It's time for winter blend.

Re: Mileage declining - Why?
 

Is this 'winter blend' usually something that's noted at the station? I have not noticed anythig stated.

As I said in my original post (although I may not have been clear) I used the vehicle last winter and the mileage was closer to my average.

Re: Mileage declining - Why?
 

Colder and denser air results in more fuel dump at the injectors. What is the difference in temperature now from last winter and what is the time frame for the colder weather?

Re: Mileage declining - Why?
 

Temp now vs last winter is about the same (it's been unusually cold here recently so even though we're still in fall, we have had winter temps).

Re: Mileage declining - Why?
 

Sounds like a mix of colder temps and different fuel. Keep a close eye out of stickers on the pump that state something like "May contain up to 10% Ethanol".

You may want to look around at other pumps in your area if you always go to the same station.

Re: Mileage declining - Why?
 

I'm guessing the only seasonal-related statement you're likely to see is on the diesel and E85 pumps.

Re: Mileage declining - Why?
 

Sascol-

We need to know the city and state you are using your car in.
Fuel varries quite a bit.
Not only does fuel vary from state to state, it can vary from city to city and season to season. There are over 50 blends of gasoline used in the U.S. alone. That's ONE reason why prices are high(er). Too many custom blends out there.
Temperatures will have have a big effect on MPG as well.
And it's not always gradual.
The battery operates one way above 50 degrees, and another way under 50 degrees. So you can see a drop all at once for example.

Re: Mileage declining - Why?
 

I am in Charlotte, NC
I'm trying to compare my mileage now to when we had similar temps earlier in the year (Feb/March).