Average MPG less than 20mpg, am I alone?

FWIW: My '23 CX5 is 14 months old, has 7,900 miles on it, no turbo. I went to my sis's for Xmas yesterday, is about an 83 mile round trip.

I got 33.4 MPG, no interstate, country driving, went through about 4 small towns.
 
Out of curiosity, why would you use anything other than 87? No advantage to it for your NA motor.
I had several inquires on this subject - mpg on the CX-5 -2.5 N/A
and the service mgr at the #1 dealer in my state ( claiming to be top 3 in country ) - said ...that using PREMIUM fuel in the NA will not only increase hp / torque ..but will deliver better gas mileage - period - no if ands or buts -
- This due to the unique nature of the high compression 13:1 / engine( usa ) - He did say the computer will adapt to lower octance fuels and run fine on either -
so i looked at the OM - and it only gives a range of fuel 87-91 minimum - and interestingly ( as we know ) theres no sticker on the fuel cap or door stating ...use 87 regular ...as is on many other NA engines - I do notice a big difference with premium 91 - and now its come way down in price -
 
I had several inquires on this subject - mpg on the CX-5 -2.5 N/A
and the service mgr at the #1 dealer in my state ( claiming to be top 3 in country ) - said ...that using PREMIUM fuel in the NA will not only increase hp / torque ..but will deliver better gas mileage - period - no if ands or buts -
- This due to the unique nature of the high compression 13:1 / engine( usa ) - He did say the computer will adapt to lower octance fuels and run fine on either -
so i looked at the OM - and it only gives a range of fuel 87-91 minimum - and interestingly ( as we know ) theres no sticker on the fuel cap or door stating ...use 87 regular ...as is on many other NA engines - I do notice a big difference with premium 91 - and now its come way down in price -
Sorry Antoine but I had to reply to this.

Nope. Your SM is not more of an authority than Mazda themselves... If the NA motor made more power with higher octane it would most certainly be noted by Mazda. What reason could you think of that they wouldn't tell the customer this? They went to great lengths to make graphs and list the power differences on the 2.5T so why wouldn't they do the same for the NA motor if it was true?

As an aside, they won't have a sticker telling you to use 87. They would only do it if something higher was needed. Higher octane won't hurt anything, but in the case of the NA, it won't help either.
 
Sorry Antoine but I had to reply to this.

Nope. Your SM is not more of an authority than Mazda themselves... If the NA motor made more power with higher octane it would most certainly be noted by Mazda. What reason could you think of that they wouldn't tell the customer this? They went to great lengths to make graphs and list the power differences on the 2.5T so why wouldn't they do the same for the NA motor if it was true?

As an aside, they won't have a sticker telling you to use 87. They would only do it if something higher was needed. Higher octane won't hurt anything, but in the case of the NA, it won't help either.
I get the same answer from every reputable mechanic and as well , the owners manual- attached ( which is ambiguous for a reason ) stating in the 2.5NA 22,23.24 ( same as other years) runs on regular unleaded fuel 87-91 octane , and thus when you speak to an educated Mazda service writer - which I have - they will tell you the higher compression 13:1 compression ratio engine in the NA will deliver more power and better gas mileage on premium fuel. Here a guy whos well known for his straight talking advice which I almost always agree with ....and he says that you should use regular 87 on most everyday car gas engines in our biggest makers ,, Toyota , NIssan , Honda etc ...EXCEPT ..he leaves out MAZDA and states " with a few exceptions" such as vehicles with HIGHER COMPRESSION engines. Its good to debate these things as its the #1 most asked question of mechanics - HE also states that you should follow whats on the gas door --which on the CX5 NA there is no sticker saying either 87 or 91 , but in the OM its there ,,,that 91 is included ...hmmm ..wonder why ?
Will it run on 87 ? Yes - Just less power less mpg -
Last note -- if one reads the fuel rec page ( which I attached )fuel below the 87-91 minimum fuel requirement... states that fuel BELOW 87 octane can cause " engine knocking and SERIOUS ENGINE DAMAGE " ...so if you are using 87 and the fuel happens to be just off by a slight amount below 87 ...then you are potentially causing serious engine damage ...so why not air on the side of caution and at least go 89 and my argument is for 91 0r 93 if you have access to it .
 

Attachments

  • F4523B9E-F358-4629-80BF-D17E4ED7F956.jpeg
    F4523B9E-F358-4629-80BF-D17E4ED7F956.jpeg
    94.9 KB · Views: 34
Last edited:
Can low MPG indicate brake issue?
If you take one car that shreds brake pads in 10-15k, and compare its MPG to another same model car that runs on same brake pads for 50k, would MPG difference be significant?
 
Can low MPG indicate brake issue?
If you take one car that shreds brake pads in 10-15k, and compare its MPG to another same model car that runs on same brake pads for 50k, would MPG difference be significant?
Im not sure I understand that question - if you have a warped rotor or rotors, that can definitely effect the rolling resistance thus gas mileage - If you have two exact vehicles that have that big of a difference in brake pad wear - all other factors being identical - its possible one car could be getting worse mileage due to an aggressive driving habit which manifests itself in heavy excessive braking ..or you could just be driving around with one foot on the brake and one on the gas - the possibilities are to numerous to consider relevant
 
OP asks why his MPG is so low
I'm wondering how often they have to change brake pads, as there might be a connection
my bad-- didnt read the op again- I would say thats something to consider and have it checked out by a brake expert -
 
you should follow whats on the gas door --which on the CX5 NA there is no sticker saying either 87 or 91 , but in the OM its there ,,,that 91 is included ...hmmm ..wonder why ?
Will it run on 87 ? Yes - Just less power less mpg -

Just to clarify.

The image you attached refers to 87 octane or above (91 RON or above). RON (research octane number) is used in countries such as Europe, Australia and New Zealand, among others. US, Canada, and Mexico use AKI, which is the average of the RON + MON. The AKI is represented as octane rating at the pump. This means that 87 octane = 91 RON, and the manual is stating that 87 octane or above can be used. So yes, you can use 91-93 octane (which is 95-98 RON) in a car that is designed for 87. However, any benefits that might come from the higher octane are a wash at best. You'll get a few more miles out of every tank but you'll also be paying more per fill. Maybe an extra $100-200 per year to run premium fuel in an engine designed for regular, to slightly reduce the chance of engine damage from a problem the car doesn't have (engine knock - something it is not known for).
 
Side note…Let’s remember to keep threads on topic, this one is about MPG…Thanks.
I know its a stretch ...but ceramic coating improves fuel efficiency -- I believe I mentioned it in another post -- although minor , it does even more so on aircraft - Thanks
 
Just to clarify.

The image you attached refers to 87 octane or above (91 RON or above). RON (research octane number) is used in countries such as Europe, Australia and New Zealand, among others. US, Canada, and Mexico use AKI, which is the average of the RON + MON. The AKI is represented as octane rating at the pump. This means that 87 octane = 91 RON, and the manual is stating that 87 octane or above can be used. So yes, you can use 91-93 octane (which is 95-98 RON) in a car that is designed for 87. However, any benefits that might come from the higher octane are a wash at best. You'll get a few more miles out of every tank but you'll also be paying more per fill. Maybe an extra $100-200 per year to run premium fuel in an engine designed for regular, to slightly reduce the chance of engine damage from a problem the car doesn't have (engine knock - something it is not known for).
Ok we somewhat agree -- yet the " car " was not designed to run on 87 ..it will run on 87 -- it has more power , less knock potential and better fuel economy on 91-93 and is a high compression combustion engine which is unlike all other vehicles in its category- It is capable of running on anything ABOVE 87 so it recognizes the fuel type and adapts accordingly - 87 being the absolute lowest octane it will operate on without potential serious complications

- The information on high compression engines shows 91-93 ( premium fuel ) demonstrates improved overall performance/ mileage --( yes more $$ ) - so if you read the caveat below the 87 rec, it states that fuel below 87 can cause knocking and potentially serious engine damage - so why " walk the line "
at the edge of the damage zone ? What if the fuel has somehow been processed or is in a condition of being 86.9-or lower ? ( an example )- then you are risking damage ....correct ? -- forget performance or gas mileage ..staying on point ...or the " edge " of point -- Why not go 89 and remove that risk --if you think 91-93 is not warranted ? This is definitely about gas mileage -- as its cost per mile based on fuel choice -- I suppose the performance debate is off topic .. I see fuel costs pretty low now compared to 2 years ago .....and Im getting 91 top tier around $3.42 -89-$3:20 87-$3.09- chevron, texaco ..shell is a bit more
To some this might sound like were beating a dead horse , yet its one of the issues which has many owners confused more than anything else -- The reason , were dealing with government regulations , corporate sales and marketing , owner based preconceived /dated knowledge bias , and most of all owners not understanding what type of engine and technology they have... i.e. the range of its functional capabilities and what are the ramifications of operating at those limitations ?

The latter is where were are , in the debate of what the engine will run on safely and what it will run on optimally ( gas mileage , performance ) - Which Mazda would prefer not to dabble , because they want to straddle the line of a vehicle which pleases the penny pinchers that put in corner store grade regular and get great gas mileage, and those who want a vehicle that has good performance attributes and more power. They want to serve both masters -
After all Mazda installs an expensive system which they invested unknown $$$ perfecting to shave a few miles off the window sticker MPG #s--- cylinder deactivation- but then again the Corvette C8 is a nearly identical engine type, with similar compression , naturally aspirated and has cylinder deactivation ....only major differences are its a V8 with dry sump - which I wish the CX5 had ! Runs on ...premium 91-93
 
Last edited:
Ok we somewhat agree -- yet the information on high compression engines shows 91-93 ( premium fuel ) shows improved overall performance/ mileage --( yes more $$ ) - so if you read the caveat below the 87 rec, it states that fuel below 87 can cause knocking and potentially serious engine damage - so why " walk the line "
at the edge of the damage zone ? What if the fuel has somehow been processed or is in a condition of being 86.9-or lower ? ( an example )- then you are risking damage ....correct ? -- forget performance or gas mileage ..staying on point ...or the " edge " of point -- Why not go 89 and remove that risk --if you think 91-93 is not warranted ? This is definitely about gas mileage -- as its cost per mile based on fuel choice -- I suppose the performance debate is off topic .. I see fuel costs pretty low now compared to 2 years ago .....and Im getting 91 top tier around $3.42 -89-$3:20 87-$3.09- chevron, texaco ..shell is a bit more

I had a nice, long reply typed out for you, but I think I will just disengage.

Back on topic please (sorry for my part in the distraction).
 
Last edited:
I had a nice, long reply typed out for you, but I think I will just disengage and let your replies and assumptions speak for themselves. If I could use the Ignore feature I would, but I need to be able to see what you post.

Back on topic please (sorry for my part in the distraction).
For a moderator, this is a pretty poor response to someone. Telling them if you could ignore them you would and the implication that this person is stupid and you'll just let them keep posting and what? We'll all see the error of their ways? Do better.

Edit: This is why mods should not be able to and shouldn't post in the forums.
 
I had a nice, long reply typed out for you, but I think I will just disengage and let your replies and assumptions speak for themselves. If I could use the Ignore feature I would, but I need to be able to see what you post.

Back on topic please (sorry for my part in the distraction).
My discourse is a search for the truth , and what is and isnt. Its not about you.
If you choose you bow out of the discussion , thats fine , but using some personal angle insinuating that I am " off topic " or some other cop out instead of sticking with fact based opinions is weak.
I gave an opinion based on a post about 87 - I supported my opinion with data , from a reputable mechanic and the owners manual -- you just rebutted with your opinion only...which is precisely why this subject is so mired in confusion - if you have data that supports your belief I would possibly change my mind - but I haven't seen it .
 
Last edited:
I don't think I ever responded to this thread, but our old '19 CX-5 only once achieved MPG's above 20. That was on a long highway trip we took in 2020. It was always hovering around 18MPG's, which was in mixed driving conditions. I used only 93 octane early on, but switched to 87 after realizing we didn't spend much time above 4k RPM, so no benefit in using it. The manual states 87, or higher, just like all manufactures, so that's what we went to. Our MPG's stayed consistent, only decreasing slightly during the winter months, as expected.
 
For a moderator, this is a pretty poor response to someone. Telling them if you could ignore them you would and the implication that this person is stupid and you'll just let them keep posting and what? We'll all see the error of their ways? Do better.

Edit: This is why mods should not be able to and shouldn't post in the forums.

I never made such an implication, that was an assumption on your part, though it was likely based on the wording I used. I'll remove the ignore comment, that was unnecessary. I'll leave the exchange up for context, but will remove myself from the conversation.

As a moderator I try to be less biased in my posts, but I often post here as a member with my own opinions too. Sometimes I cross lines and I apologize for that. But that is a me problem, not a moderator problem.
 
I don't think I ever responded to this thread, but our old '19 CX-5 only once achieved MPG's above 20. That was on a long highway trip we took in 2020. It was always hovering around 18MPG's, which was in mixed driving conditions. I used only 93 octane early on, but switched to 87 after realizing we didn't spend much time above 4k RPM, so no benefit in using it. The manual states 87, or higher, just like all manufactures, so that's what we went to. Our MPG's stayed consistent, only decreasing slightly during the winter months, as expected.
Did you ever calculate the gallons and miles yourself? Maybe your readout was off. It's not normal for these cars to be that low. My average after 3 years of ownership of my 2020 FWD Touring (NA with cylinder deactivation) was 26.5 mpg.

My 2023 Turbo is hovering around 22 but the winter is taking its toll. It was better with the summer gas and no snow to plow through.
 
Last edited:
Did you ever calculate the gallons and miles yourself? Maybe your readout was off. It's not normal for these cars to be that low. My average after 3 years of ownership of my 2020 FWD Touring (NA with cylinder deactivation) was 26.5 mpg.

My 2023 Turbo is hovering around 22 but the winter is taking its toll. It was better with the summer gas and no snow to plow through.
Yes, I saved receipts and had a tracking spreadsheet. I'm anal that way. :)
 
Back