Better gas mileage for cx7

I had an oxygen sensor replaced.

Prior to that I got 20 mpg in the city for my CX7.

Now I am getting 21.5 mpg.

Could that increase be due to the replacement of the O2 sensor?


Yes it could. Warmer weather could also be part of it.

Only got 20MPG ? Every time ? Must be something wrong with my vehicle because I get a range from 31.4 to 35.3 and sometimes more or less than those. Also it is about time for the fuel mixture to change from cold weather to warmer .

Yes every time. I get 28 hwy when using the cruise control.

My 2009 has a 2.4 Liter turbo charged.

Sounds like your cx7 must be newer or have smaller engine

Here are the specs.

2009 Mazda CX-7 · Specs

MSRP $23,900 - $28,400 ·

Fuel economy Up to 17/23 mpg (city/highway)

Thanks for the info. Do cars get lower mpg in colder weather?

Yes they do . Which is why I suspect you are not checking your miles per gallon the proper way . Very few vehicles get the same MPG every tank and most do not exceed the city / highway rating every time.

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Your mpgs sound about right. Folks with the 2009 average 18 mpg on Fuelley:
Mazda CX-7 MPG - Actual MPG from 123 Mazda CX-7 owners (

In a CX-7? A car that big gets 35mpg?

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If you do the same sort of driving, same routes and driving habits, your mpg will be fairly consistent. Not necessarily spot on but within a fairly narrow range. Mine certainly is.


While it varies a bit depending on the season, within a season my gas mileage varies very little, probably because my driving patterns and behaviors are quite consistent.

As an example, in local driving, my mileage in the winter is 23-24 mpg, but once the weather warms-up, my mileage for local driving is almost always in the 25-26 mpg range. For longer trips, no matter what the season might be, my typical mpgs are in the 27-29 range.

I said my vehicle ( I don’t have a CX7 ) . The point being that it is rare that someone gets the same MPG every time and exceeds the rating every time . Which goes back to I doubt if he is checking his MPG correctly since he asked if winter weather reduced miles per gallon.


Oh, I see. I rarely bother to check mileage by dividing miles by gallons anymore. I just use the readout on the instrument panel. Whether it’s accurate or not isn’t important, just that the reading is consistent.


I consider the mpg readout to be a “cheap and dirty” diagnostic tool. If it took a nosedive, and if I hadn’t been in stop & go driving, that would indicate a possible problem, IMHO.

But, after doing repeated comparisons of the readout with actual paper & pencil calculations, I have confirmed that the readout is a consistent .4 mpg optimistic. That’s close enough for me.


Sounds about dead on. I mean, when was the last time your pencil was calibrated? :laughing:


Yes, a lot lower.

I know how to check my mpg. Been doing it over 40 yrs. Who said anything about getting the same mpg every tank? :slight_smile:

That’s impressive that the gauge is so accurate compared to manually calculating mpg
. :slight_smile:

Better than my Hyundai, which is 7% optimistic.
I stopped doing manual calculation after the first few months.
On a road trip getting a real 30 mpg it displayed ~32.
Puttering around town in the winter getting 20 mpg it displayed ~21.5.

You did by stating one number for city and one for highway and then asked if colder weather reduced mpg. If you were checking you would have a range from low to high .


Where’d he say that?