Fuel efficiency 2.5T (Premium vs Regular fuel)

[nwbutcher]

'22 CX 9. Just wanted to get others opinions/observations on fuel efficiency running regular fuel vs. premium. I see a lot of post on the power difference, but haven't seen anything on efficiency. This weekend I needed to take my kiddo to camp. It was about 60 miles out and back. virtually all freeway. I was just finishing up the first tank of premium fuel I had tried. I started the trip with the gauge reading 21.9 MPG. after 60 miles of mostly flat to rolling hills, no congested traffic and a light tail wind, the economy gauge was only at 22.7 MPG. I had the cruise set most of the time at 3-5 over the speed limit. I was keeping an eye on the economy gauge, and I would guess I would be at maybe 25-26 MPG if it didn't have the historical average in there (the first part of the fuel tank fill). Now for the return trip I filled the mostly empty tank with regular gas at a station right next to the freeway. The return trip was mostly the same as the trip out. Mostly flat/rolling hills, slight head wind and cruise set 3-5 MPH above the speed limit (I checked and there was virtually no difference in elevation between the start and endpoints of the trip). After the initial drop of getting on the freeway I was quickly over 25 MPG, and by 30 miles I was getting over 29 MPG. By the end (except for the final mile of traffic lights, turns and city streets) I was at 30.3 MPG.

I know my observations are not scientific, and barely better than a guess. But does anyone have any longer term data such as multiple tanks and logs comparing regular vs premium fuel in the 2.5T and the associated fuel economy.

 

[11E20]

I kept some records when I first bought my 2019 CX-9 GT and did manual mileage calculations and found that the trip computer mileage was quite accurate. I reside in a rural area and drive a mix of back roads and highway and the best I've ever gotten is 24 MPG. Typically I get 21-22 MPG running unleaded regular gasoline.

 

[PTguy]

I have not seen a difference in fuel consumption, but I don't keep accurate records. I notice better engine response at freeway speed with the high octane gas. About consumption...the hi test savings would have be enough to equal or improve the fuel cost per mile, not just better mpg.

 

[GTEyes]

I didn't notice any fuel economy difference when I was running higher test gas. The engine pulls harder in the higher revs with the higher octane fuel. I am finding that my best fuel economy on the highway is around 105 km/hr. My drive in to work this morning had a trip average of 7.9L/100km (Just shy of 30 MPG) which I am impressed with. For reference my old 2018 Mazda6 Signature averaged 7.4L/100kms at 113 km/hr...

 

[Fruitwolf]

No difference in mpg but the engine runs smoother with more torque using high octane.
I forgot to add… I get better mpg when using non-ethanol fuel.

 

[sm1ke]

I have not kept accurate records, but I do recall getting a few more kms from a tank of premium. I ran premium only for the first couple of years, then ran regular only for a short period of maybe 2 or 3 months? My commute during this time was the same as with premium fuel, and I also used the same engine oil. I think the difference was maybe an extra 10-20 kms at most. Pretty minimal.

 

[scoobdude]

Not sure if yours has it but on our cx5 you can hold down the dimmer switch and see actual instant numbers instead of the DTE and MPG gauges.

 

[ctbale]

Cross country drive with 87 octane.

 

[alfamale]

Fuel economy plumets above 60MPH in these things largely due to the final gear ratio causing the engine to rotate faster than the average 4 cylinder turbo.

 

[Fruitwolf]

Fuel economy plumets above 60MPH in these things largely due to the final gear ratio causing the engine to rotate faster than the average 4 cylinder turbo.

Yep. Even the difference between 75mph and 81-82 mph is huge.

 

[dunhillmc]

Did you reset the counter at each fill-up?

 

[cz5gt]

Same observations.
50-55mph I can get 33 mpg, even 34mpg on flat surface. around 65mph gets you more or less 30 mpg, more than 70mph usually mpg drops. And above 80 its thirsty. Thats with 91.

 

[Z31]

Same observations.
50-55mph I can get 33 mpg, even 34mpg on flat surface. around 65mph gets you more or less 30 mpg, more than 70mph usually mpg drops. And above 80 its thirsty. Thats with 91.

Same here as well. I find even the 35-45mph range very efficient (according to the instant read-out anyway). Must be the short final drive. Maybe sacrificing a bit of highway mileage for daily commute efficiency.

It's taking a bit to get used to the tiny bit of throttle required to keep it moving. It feels like a 1/8" difference between 30mpg and 20mpg. As much as I hate drive modes, it probably could benefit from an "eco" mode, or just have regular mode give a bit less aggressive throttle tip-in. I'm sure having that over-exaggerated torque blast is intentional though, especially to wow people shopping!