2017/18 Real World MPG

2017 AWD with 5,400 miles.

In the winter and cold months I let the car warm up a couple minutes. My mileage accounting for cold and warm-up: 24 city, 28 highway, 26 combined

In the summer months I get: 26 city, 30 highway, 27.5 combined

Hope that helps!

Is this based on the trip computer or your manual calculations?

If I posted what the trip computer tells me, it would be 31.5 MPG.

If I post what I'm actually getting, it would be 28.5 MPG.
 
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Of course...if you fill-up in Miami at 2pm during the summer, and stop the pump on the first click...your calculated MPG will not be comparable to filling up in Alaska during the winter, and stopping the pump on the fifth click.

But you can get reliable, accurate, consistent MPG ratings by simply using the same fill-up approach under reasonably similar conditions.


If you fill up in Alaska, like Canada, your winter mpg will be lower than in the summer, not just because of fuel expansion/contraction, BUT, in colder climates additives are put in the fuel to create what we call "Winter Gas", at least in Canada, which provides extra protection by helping with cold weather starts and helping to prevent fuel line freezing. The unfortunate downside is lower mpg which is why I don't put much stock into the mpg reading on my vehicle, at least up here in Canada during the winter-time.
 
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Is this based on the trip computer or your manual calculations?

If I posted what the trip computer tells me, it would be 31.5 MPG.

If I post what I'm actually getting, it would be 28.5 MPG.

My numbers were based off of a full tank to empty tank average. I take my miles driven for said tank and divide it by actual gallons going into the car from the pump. For the most part it seems to match up with my trip computer. :shrug:
 
And don't forget that the correlation between the mileage readout on Trip B [reset each time] and the mileage app is wildly variable. I would expect them to use the same inputs, so the calcs must vary, or the two systems must operate on their inputs differently. The more you idle, the less they agree. They are only approximate. And should idling time count against the car's fuel efficiency? No, but it contributes to fuel consumption.

If you always record the gas you put in and miles traveled, over time you will get a good answer. Since there are so many variables [temps, blends, pumps, etc], the longer the length of time you calc your average, the more accurate it will be. And it will change given changing conditions.
 
My trip computer has overstated by 2-3.5 MPG, on all but about 2 fill-ups across the 10K miles I've driven.

It's no surprise that trip computers generally overstate MPG, and very rarely (except for you) understate MPG. Would a car manufacturer rather have me believe I'm getting 31 MPG or 28 MPG?

My point is, your true MPG is likely significantly lower than what the trip computer is telling you.

If that is the case you need to bring it up to your dealer and write to NHSTA. While as I said - no one is out to fool anyone and a variance of .5 to 1 mpg either side is normal. 2-3.5 is a huge problem. I might be the only one who has seen it being understated. In a similar way you are the only person on this forum that has a 3.5 mpg variance. This is pretty huge.
My MPG is calculated in an approx. way as yours. Gas filled to first click, inverted and multiplied with miles driven. So my actual MPG is not in debate. I have had 30 when the dash had 28.X I have had much smaller variance of .5 mpg as well. I may have overstated dash mpg.
But 2-3.5 - there is something wrong with your CX-5. I would assume if it was EVERY CX-5 we would have had more threads.
 
Is this based on the trip computer or your manual calculations?

If I posted what the trip computer tells me, it would be 31.5 MPG.

If I post what I'm actually getting, it would be 28.5 MPG.
What size tires and wheels are you running?
 
In a similar way you are the only person on this forum that has a 3.5 mpg variance. This is pretty huge.

How do you know that I'm the only person experiencing variances like this?

I think the majority of owners simply go by what the trip computer says, and report that (inflated) number here.

Unless people start reporting what their calculated MPG versus trip computer MPG is, we will never know.
 
How do you know that I'm the only person experiencing variances like this?

I think the majority of owners simply go by what the trip computer says, and report that (inflated) number here.

Unless people start reporting what their calculated MPG versus trip computer MPG is, we will never know.

There are many mpg minded folks here who have plotted mpg vs steady speed graph and the mpg thread running 60+ pages. These folks calculate mpg and post. Plus no one on these threads made a claim like you have. If I have to choose between calling them idiots or your CX-5 having an issue I will select the latter.
 
I think the majority of owners simply go by what the trip computer says, and report that (inflated) number here.

Unless people start reporting what their calculated MPG versus trip computer MPG is, we will never know.

OK, so I'll report in. 96 fill-ups, all documented on Fuelly and I've kept track of the instrument reading for each tank in the note section. For my CX-5 my calculated is 33.7 mpg while the weighted average of the instrument readings is 33.0 mpg. So the computer is under-reporting my fuel mileage by 0.7 mpg.

The variances I see are most likely caused by my inability to fill to the same point each time, but there is no doubt in my mind that that my CX-5 under-inflates, not over-inflates mpg.


BTW, I do know something about over-inflated mpg numbers. My wife has 2010 Nissan, with over 300 fill-ups on Fuelly and it gets over 2 mpg less than what the car says it's getting.
 
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OK, so I'll report in. 96 fill-ups, all documented on Fuelly and I've kept track of the instrument reading for each tank in the note section. For my CX-5 my calculated is 33.7 mpg while the weighted average of the instrument readings is 33.0 mpg. So the computer is under-reporting my fuel mileage by 0.7 mpg.

The variances I see are most likely caused by my inability to fill to the same point each time, but there is no doubt in my mind that that my CX-5 under-inflates, not over-inflates mpg.

This is a great data point. Thanks for posting.

But can you confirm that you own the previous generation CX-5, not the current generation?
 
There are many mpg minded folks here who have plotted mpg vs steady speed graph and the mpg thread running 60+ pages. These folks calculate mpg and post. Plus no one on these threads made a claim like you have. If I have to choose between calling them idiots or your CX-5 having an issue I will select the latter.

I've only read one post (just recently posted) comparing the calculated MPG to the trip computer MPG.
Could you link to the MPG thread you mention. I haven't seen it.

Also, could you point to where I called people "idiots" over this fuel economy topic?

I've only said that you shouldn't rely on your trip computer's MPG estimate.
 
Fuelly.com is pretty consistent for all year models from 2014-2018 at around 25.5 for combined city/highway MPG. Probably +1 for FWD and -1 for AWD on that number.
New turbos will probably be around 21-22 combined but worth it in my opinion.
 
I've been using Fuelly to track mileage for my 2018 CX-5 GT AWD since shortly after I got it in Feb 2018. With 50 fill-ups and 15,223 miles tracked, I am averaging 28.5 mpg combined.
 
But can you confirm that you own the previous generation CX-5, not the current generation?

Yeah, I've got a 2016, but it's got the Mazda connect system and command knob, so I think the methodology it uses to calculate mpg should be very similar, if not identical, to Gen 2.

Over the 3.5+ years I've been here, I've seen posts claiming all scenarios, under, over and accurate mpg readings from the on-board system. My advice to all: run the numbers for your own car and decide for yourself.
 
OK, so I'll report in. 96 fill-ups, all documented on Fuelly and I've kept track of the instrument reading for each tank in the note section. For my CX-5 my calculated is 33.7 mpg while the weighted average of the instrument readings is 33.0 mpg. So the computer is under-reporting my fuel mileage by 0.7 mpg.

The variances I see are most likely caused by my inability to fill to the same point each time, but there is no doubt in my mind that that my CX-5 under-inflates, not over-inflates mpg.


BTW, I do know something about over-inflated mpg numbers. My wife has 2010 Nissan, with over 300 fill-ups on Fuelly and it gets over 2 mpg less than what the car says it's getting.

Only 96 fill ups? Just a baby...
 
So, we are now on our 3rd tank. 1st was dealer fill, so I didn't calculate mpg's manually. Our 2nd fill-up was with 93 octane, just to see if we could notice the HP gain (we didn't, but it's winter). The tank took 12.5 gallons. We got a whopping 180 miles out of the last tank. Math says that's 14.4 mpg's. The on-board computer, which I reset after the last fill-up, showed 14.5. Pretty accurate if you asked me.
 
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