CX-5 MPG with Turbo vs NA?

I would never go by what the gauge shows, and hope nobody does ...
Always fill up, reset mileage counter, then fill up and calculate ...
 
One problem with the mpg calculation method is with small tanks. If you don’t get the tank consistently full each time, that could skew your calculated mileage by 2-3 mpg either + or -. Over time, however, you will get a sense of the vehicle‘s true mileage, especially if you keep a written log.

I keep a 3”x5” spiral bound notebook in the glove box where I write down the details of each fill up, including: date, total miles, gallons purchased, cost of the fill up, $/gal, and mpg. Sometimes I include a note that the fill up was town driving, or all hwy miles. Been doing this for 40 yrs.
 

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Interestingly, this is the 1st car I've had where the computer MPG is within 1 mpg of my manually calculated refill numbers - actually probably within .5 mpg, and the Costco pump that limits top-off probably helps in the refill consistency amount put in. The 2011 Miata is terribly off read-out vs manually calculated
 
I’ve read were top-offs can damage your vehicle’s vapor collection system. I’ve been topping off for 50 yrs with no apparent consequences. Does anyone with a newer CX-5 have any 1st hand experience with topping off vs. damaging your car’s emission system? I’ll quit doing it if it is a factor on my 2021 CX-5.
 
I’m testing what the mileage gauge says on the dash vs. calculated mileage. Only 3 fill ups so far, so nothing conclusive, but my calculated mileage seems to be 1-2 mpg less than the gauge shows. Time will tell how accurate the guage is.

I am wondering if any other folks have checked to see how accurate the dash mpg guage is.
The times I calculated by the pump the numbers matched the dash readout pretty closely.

Accuracy calculating by the pump relies on the accuracy of the pump, so there is some possibility of error there.
 
What does it matter if the gauge is slightly off?
If it the computer says I got 24.6 mpg but in reality I only got 24.3 mpg.... so what?
That's a good point. I like the gauge for checking the performance of my own vehicle on different routes or at different speeds, but they collect gas taxes at the pump. If I had to put it on my tax form it might be an issue. Otherwise, you get what you get. As long as you don't run out ( of gas!).
Once I was driving cross country and there were extremely unfavorable headwinds. The gauge kept me informed so I wasn't surprised that the mpgs were down by 20-30%.
 
I’ve read were top-offs can damage your vehicle’s vapor collection system. I’ve been topping off for 50 yrs with no apparent consequences. Does anyone with a newer CX-5 have any 1st hand experience with topping off vs. damaging your car’s emission system? I’ll quit doing it if it is a factor on my 2021 CX-5.
I can’t say about the CX-5, I do know that other manufacturer’s vehicles can be damaged. The fuel backs up into the venting system, throws codes and is costly to replace. I too used to top off, but my last vehicle “trained” not to do so. You seldom get too much more in anyway.
 
What does it matter if the gauge is slightly off?
If it the computer says I got 24.6 mpg but in reality I only got 24.3 mpg.... so what?

I agree. A change that small could be the difference in pumping. Also, I find the average of two fill ups calculated manually to be very similar to what is observed on the car computer.
 
I can’t say about the CX-5, I do know that other manufacturer’s vehicles can be damaged. The fuel backs up into the venting system, throws codes and is costly to replace. I too used to top off, but my last vehicle “trained” not to do so. You seldom get too much more in anyway.
If the gas gets into the tube that leads to the charcoal canister it contaminates it.
 
The times I calculated by the pump the numbers matched the dash readout pretty closely.

Accuracy calculating by the pump relies on the accuracy of the pump, so there is some possibility of error there.
Yes, measure calculated at the pump is actually always, 100% of the time, a few tenths or so better than the dash read out for me.
 
The problem with asking someone their mix of “highway” and “ city” driving is that...the definition of both varies, a lot. For highway driving, some folks drive 65 mph on flat ground near sea level while others drive 85 mph in the mountains. For non-highway driving some will drive where there are stoplights every block, some were there are lights ever one or two miles apart. Some drive with a heavy foot, some drive for economy. With such a wide variation in driving styles it’s very tough to get a true idea of the differences without a large sample. Results from five people won’t do much good.
 
The problem with asking someone their mix of “highway” and “ city” driving is that...the definition of both varies, a lot. For highway driving, some folks drive 65 mph on flat ground near sea level while others drive 85 mph in the mountains. For non-highway driving some will drive where there are stoplights every block, some were there are lights ever one or two miles apart. Some drive with a heavy foot, some drive for economy. With such a wide variation in driving styles it’s very tough to get a true idea of the differences without a large sample. Results from five people won’t do much good.
My 2015 on the same commutes averaged about 24-25. I am doing 2mpg better with the 2019 turbo.
 
Do you have the turbo or non-turbo engine, and what is your % mix of city/hwy driving? Is your mpg calculated or what the mpg readout says?
Non turbo. I drive about 40 city 60 highway. The 27.2 is what my display shows. It had reset last year when I had disconnected the battery, and since then it has 27.2.
 
2.2 diesel (2019 USA) .... 32.5 mpg avg weekly mix and 35.5 mpg straight up highway travel
The EPA MPG ratings for 2.2L diesel CX-5 AWD (28/31/29 city/hwy/combined) definitely are lower than your real world experience. On the other hand your mpg’s on 2.2L diesel CX-5 are still lower than those diesel CX-5’s in other countries, especially the highway mpg.
 
Both my 2019 GT and wife’s 2018 Touring average slightly over 30mpg per tank, every fill up.
The CD helps with many side roads are 35-45 mph limits in our area, almost no stop and go traffic, and normal highway speeds of 65-70mph.
Despite hilly Massachusetts terrain both our cars are way exceeding Mazda’s 26 mpg combined estimate.
 
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