Turbo gas mileage on regular VS premium?

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Phoenix
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Okay, this is not a thread on the general performance facts and myths of premium gas. Rather, since the Turbo does have different power outputs depending on the gas used, has anyone noticed a difference in MPG?

This might be hard to determine since many might drive more spirited on premium (zoom-zoom) and more conservatively on regular.
 
I've seen lots of anecdotal comments that you get better mpg with premium but unless premium is only a few cents more than regular it doesn't make much sense. In my neck of the woods premium is at least $.60 cent more per gallon. So, if you're getting 3 more miles per gallon premium would have to be no more than $.22 per gallon compared to regular.
This is based on my mpg of apprx. 24.5.
 
Just a quick addendum - got gas this morning. Regular was 1.89. Premium was 2.79.
Big difference. Premium would have to provide mucho more mpg to make cost effective.
 
On a CX-9, I have noticed zero difference in MPG when using premium 93 octane versus 87 octane regular gas.
 
When I first got our 2020 CX 5 Signature turbo I used premium gas just to test it for added performance. I only put 2 - 3 fill ups of premium in and recall I was getting 26.5 MPG. Switched to regular and it now gets ~25 MPG, frankly I didn’t notice a performance difference so I’m sticking with regular.
 
While Mazda is very specific about difference in HP between Premium and Regular, they say nothing about changes in fuel economy -- which suggests no difference.

It's possible that you might get slightly better fuel economy on premium, but definitely not enough to make up for the difference in price of premium fuel vs regular fuel.
 
On a CX-9, I have noticed zero difference in MPG when using premium 93 octane versus 87 octane regular gas.

I also have a CX-9 and echo this statement.


It's possible that you might get slightly better fuel economy on premium, but definitely not enough to make up for the difference in price of premium fuel vs regular fuel.

And this too. But I fill with premium anyway. I get a few opportunities to open it up while merging onto a couple of main roads during my daily commutes, so its worth it to me.
 
I also have a CX-9 and echo this statement.




And this too. But I fill with premium anyway. I get a few opportunities to open it up while merging onto a couple of main roads during my daily commutes, so its worth it to me.

I've only had one fill up each of reg and prem, and my butt dyno hasn't noticed a difference. I'll have to try again after acclimating my butt
 
I've only had one fill up each of reg and prem, and my butt dyno hasn't noticed a difference. I'll have to try again after acclimating my butt
If you switch back/forth at each fill-up, you are never experiencing true premium or regular.

With a 15.3 gallon tank, you are likely only pumping ~11 gallons at each fill-up.
So you are essentially just evaluating mid-grade fuel every time (with octane levels at ~89-91).
 
I've only had one fill up each of reg and prem, and my butt dyno hasn't noticed a difference. I'll have to try again after acclimating my butt

You'll only feel the difference when accelerating above 4k RPM. Also, if you had a tank of 87 and subsequently filled with 93, you've got a mix of 87 and 93 fuel in the tank, so technically it isn't really 93. You'd have to run at least a few tanks of 93 to get the full benefit.
 
You'll only feel the difference when accelerating above 4k RPM. Also, if you had a tank of 87 and subsequently filled with 93, you've got a mix of 87 and 93 fuel in the tank, so technically it isn't really 93. You'd have to run at least a few tanks of 93 to get the full benefit.

If what you say is true, and I'm probably better off with regular for several reasons. One, most of my spirited driving is initial acceleration from a stop. Second, is that we only have 91 here so I'm not feeling the 93 anyway
 
Well, 91 is what MAZDA recommends, so mixing a fill of 93 with a few gallons of 87 remaining WILL give you full benefits.

I've done the 87 vs 93 test several times now. I feel no difference in performance, but do notice that my '19 GTR idles much more smoothly with 93 than with 87. With 93 in use, I can barely tell the car is running at idle. I sense no other impact from spending the extra cash.
 
If what you say is true, and I'm probably better off with regular for several reasons. One, most of my spirited driving is initial acceleration from a stop. Second, is that we only have 91 here so I'm not feeling the 93 anyway

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Red = 87
Grey = 93

I only have 91 here and I can feel the difference when I lay into it at higher RPMs. If you were to fill with 89 vs 87, I believe you'd also get a slight bump in performance above 4k, but it would not be the full 250hp. I think with 91 I'm at around 242hp at 4k RPM, at 89 I might be around 235hp at 4k RPM.

I will also note that on 91, my engine is really quiet at idle as well, much quieter than I would expect it to be. I have not run 87 for a long time, so I don't know if there is a difference in idle noise.
 
I have ran nothing but top tier 91 octane in my CX 5 turbo. It will be a year old next week and I only have 5800 miles on it. I live in the mountains and want the extra performance of premium fuel, regardless of cost difference since I'm not consuming that much gas from commuting to work anymore.
My "A" trip odometer has never been reset, I use the "B" when I want to measure distance.
It shows 23.9 MPG average for those 5800 miles. I have checked the mileage on a 200 mile round trip freeway run and got just over 27 MPG at speeds averaging 75 MPH.
 
Where did you see that?

take it from the source:

often people get 91 RON confused with 87 pump rating.

directly from the link above:
This vehicle will perform best with fuel listed in the table.

FuelOctane Rating* (Anti-knock index)
Regular unleaded fuel87 [(R
plus01.png
M)/2 method] or above (91 RON or above)
  • U.S. federal law requires that octane ratings be posted on gasoline station pumps.
Fuel with a rating lower than 87 octane (91 RON) will negatively affect the emission control system performance and could also cause engine knocking and serious engine damage.

 
There are a lot of pumps with 85 around here. They say you don't need the octane because of the high elevation. Is that true?

I get better mpg with no alcohol but it's hard to find.
 
There are a lot of pumps with 85 around here. They say you don't need the octane because of the high elevation. Is that true?

I get better mpg with no alcohol but it's hard to find.

Your modern engine needs the required octane rating in the owner's manual. Most people who still quote this old adage are coming from non fuel injection and computer controlled engine history.

some helpful discussion


as far as no alcohol fuel.. did you mean ethanol? PLENTY of reading on that
 
Yeah, pure gas, non ethanol. Not very much around here. There us a place about 20 miles from here that has 93 octane pure gas.
 
I have tried premium, and alcohol free. I have noticed little difference between them, and regular. Therefore regular is my choice.
 
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