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Discussion Starter · #1 ·
This past weekend my wife and I went on our first real road trip in our 2017 Ecovert Premium with 6 sp MT using 87 octane fuel. It is just a summer use pleasure vehicle rather than a daily driver and we have always used premium fuel since we got it. It has very mild mods with the intent to simply enhance stock performance and reliability: Green drop-in filter, Airaid intake tube, throttle body spacer, CVF Street intercooler, CVF Y-pipe/resonator delete, Mishimoto oil catch can, and pre-gapped spark plugs. Certainly no race car, but a very enjoyable driver.

Anyway, we just completed a 700 mile road trip from central Maine to Montreal driving a mix of two lane routes and interstate plus about 50 miles in and around Montreal. Because of the current cost of fuel, I reluctantly decided to run 87 octane regular fuel. I don't drive aggressively but neither do I just putt along. No runs to redline but certainly into the upper half of the rev range.

I'm a bit surprised and puzzled because I expected mileage and performance to be noticeably less running regular vs. premium fuel. That did not seem to be the case at all. Overall fuel mileage for the trip was just over 30 mpg (verified by hand calculation). We have done this exact same trip before on same roads, same driving, etc. using premium fuel and essentially got the same mileage, i.e. just over 30mpg. An even bigger surprise was the overall driveability on regular fuel.

The engine felt very responsive and happy on 87. In fact, at over 60 mph cruising in 6th gear, it almost felt better! Same with off idle low end response. How could this possibly be?????? The only time I thought power might be slightly less was one quick pass down to 3rd gear and running to around 6000 rpm. Still good power though and didn't notice big falloff at high rpm.

I'm not suggesting that 87 octane is as good as 93, but I was pleasantly surprised at how well my car ran on this trip. I really expected a noticeable drop in performance and fuel economy.
 

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If prices don't get better I might have to remove my 93 Stage 2 tune and give this a shot.馃
 

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This past weekend my wife and I went on our first real road trip in our 2017 Ecovert Premium with 6 sp MT using 87 octane fuel. It is just a summer use pleasure vehicle rather than a daily driver and we have always used premium fuel since we got it. It has very mild mods with the intent to simply enhance stock performance and reliability: Green drop-in filter, Airaid intake tube, throttle body spacer, CVF Street intercooler, CVF Y-pipe/resonator delete, Mishimoto oil catch can, and pre-gapped spark plugs. Certainly no race car, but a very enjoyable driver.

Anyway, we just completed a 700 mile road trip from central Maine to Montreal driving a mix of two lane routes and interstate plus about 50 miles in and around Montreal. Because of the current cost of fuel, I reluctantly decided to run 87 octane regular fuel. I don't drive aggressively but neither do I just putt along. No runs to redline but certainly into the upper half of the rev range.

I'm a bit surprised and puzzled because I expected mileage and performance to be noticeably less running regular vs. premium fuel. That did not seem to be the case at all. Overall fuel mileage for the trip was just over 30 mpg (verified by hand calculation). We have done this exact same trip before on same roads, same driving, etc. using premium fuel and essentially got the same mileage, i.e. just over 30mpg. An even bigger surprise was the overall driveability on regular fuel.

The engine felt very responsive and happy on 87. In fact, at over 60 mph cruising in 6th gear, it almost felt better! Same with off idle low end response. How could this possibly be?????? The only time I thought power might be slightly less was one quick pass down to 3rd gear and running to around 6000 rpm. Still good power though and didn't notice big falloff at high rpm.

I'm not suggesting that 87 octane is as good as 93, but I was pleasantly surprised at how well my car ran on this trip. I really expected a noticeable drop in performance and fuel economy.
Is your car tuned, and if it is, is it tuned for 93 fuel?
 

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If prices don't get better I might have to remove my 93 Stage 2 tune and give this a shot.馃
If you want keep your 93 tune and save some money... Do a little research on mixing gasoline and ethanol. Wallace Racing has a free calculator!
I ran E30 on a 93 octane tune last year without any reduced performance. Now I'm running flex fuel on an E85 tune and have a slight improvement in performance. Have never done the math, but it doesn't seem like I'm using any more fuel then I did before tuning my car.
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There is no reason to expect your car to get better mileage on 93 octane. The added octane allows for more timing without detonation at or near WOT for more peak power, it doesn't do anything when you are cruising with light throttle. It only takes 10 to 20 HP to maintain 60 mph and your throttle will be barely cracked open.



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Discussion Starter · #6 · (Edited)
Coyote Chaser: I am on stock tune with the slight mods noted. Bought the car with 1300mi as a CPO with 7yr/70k warranty that I want to keep intact without question.

dgc333: That makes perfect sense! I have always gotten better fuel economy with other "toys" (motorcycles, snowmobiles, boats, watercraft) using premium fuel. However, most of those are modded and spend a lot more time operating at or nearer to WOT.

edit: I have read a number of claims here and elsewhere by owners that say they get consistently better fuel mileage running premium fuel (on stock tune). As noted, I didn't see it in this trip and will be monitoring closely over the next several weeks using 87. I'm betting very little difference in everyday driving.
 
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Also there is a very good chance that folks claiming better fuel mileage are "playing" just as much as they are cruising on that same tank, or dumping their car around in Sport , Sport plus or track modes.. add in some WOT pulls or some spirited passing on the highway and you can see where the difference might be more apparent to @dgc333 's point. Just cruising along the highway in " normal" mode at a reasonable speed is I would think a pretty accurate way to get a baseline for mileage regardless of octane rating.
 

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This past weekend my wife and I went on our first real road trip in our 2017 Ecovert Premium with 6 sp MT using 87 octane fuel. It is just a summer use pleasure vehicle rather than a daily driver and we have always used premium fuel since we got it. It has very mild mods with the intent to simply enhance stock performance and reliability: Green drop-in filter, Airaid intake tube, throttle body spacer, CVF Street intercooler, CVF Y-pipe/resonator delete, Mishimoto oil catch can, and pre-gapped spark plugs. Certainly no race car, but a very enjoyable driver.

Anyway, we just completed a 700 mile road trip from central Maine to Montreal driving a mix of two lane routes and interstate plus about 50 miles in and around Montreal. Because of the current cost of fuel, I reluctantly decided to run 87 octane regular fuel. I don't drive aggressively but neither do I just putt along. No runs to redline but certainly into the upper half of the rev range.

I'm a bit surprised and puzzled because I expected mileage and performance to be noticeably less running regular vs. premium fuel. That did not seem to be the case at all. Overall fuel mileage for the trip was just over 30 mpg (verified by hand calculation). We have done this exact same trip before on same roads, same driving, etc. using premium fuel and essentially got the same mileage, i.e. just over 30mpg. An even bigger surprise was the overall driveability on regular fuel.

The engine felt very responsive and happy on 87. In fact, at over 60 mph cruising in 6th gear, it almost felt better! Same with off idle low end response. How could this possibly be?????? The only time I thought power might be slightly less was one quick pass down to 3rd gear and running to around 6000 rpm. Still good power though and didn't notice big falloff at high rpm.

I'm not suggesting that 87 octane is as good as 93, but I was pleasantly surprised at how well my car ran on this trip. I really expected a noticeable drop in performance and fuel economy.
I have never run anything but 88 Ethanol-Free in my 2018 Mustang Ecoboost (once in a while I'll run 91 Ethanol-Free). I want to avoid the potential gumming up that ethanol is prone to cause over time, especially if gas sits in the tank longer than 30 days. I also have a 2016 F-150 Ecoboost. I usually run the same 88 Ethanol-Free without any issues. I once tried the cheaper 85 on a trip to see what would happen. The truck ran terribly. Gas mileage suffered and the truck would stall whenever I did a complete stop. I switched back to the 88 and issues quickly went away and MPG improved. I wouldn't chance 85 on my Mustang, but perhaps 87 isn't that low (I think it's the lowest recommended). For me, I'll pay extra to keep Ethanol-Free in my tank and potentially save big in the long-run by avoiding future repairs.
 

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Stopped for fuel in Ohio, I think 88 may be what we call E15 and Flex Fuel is what we call E85!??
I run E15 in my Ecoboost Fusion and E85 (which, when tested, is only E65) in my Ecoboost Mustang. No idea of what kind of milage I get, but both cars run fine with zero knock.
 

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Discussion Starter · #12 · (Edited)
In my area, difference between regular and premium is $0.70 to $0.85/gal. A few Citgo stations here offer 90 octane ethanol free "rec blend", which I use in my boats and snowmobiles. It is about $ 0.25 more than ethanol blend premium. On another fuel related thread somewhere here recently, there was a comment that ethanol free fuel was not best for the turbocharged ecoboost ......... something about charge cooling effect of ethanol or such as I recall but not sure if that is valid......

Good article Budster - thanks for the link. Pretty much summarizes what I thought I knew on the issue.
 

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Hi, new ecoboost HPP owner, just got delivered yesterday. I bought it used, certified with 6600 miles, it has the handling package also.
I鈥檓 following this thread. The dealer filled it with 87 and it seems to run great but I have nothing to compare to as of yet. Will fill with 93 when empty.
Is yours the high performance package? I鈥檓 wondering if the different tune makes a difference. I do have a link that Dyno鈥檇 87 vs 93 octane and they got a 22 whp improvement. I don鈥檛 think it was an HPP though. It was done by a site called speed factory
 

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Hi, I tend to lurk here and chime in when I think I know what I might be talking about.....When my car was completely stock I toyed between 87 and 93 octane. This was also before I read the manual that states only to use Top Tier gas no matter what octane you use. 87 is okay but 93 preferred. I was not using Top Tier gas and toggling between 87 and 93 I did not see an MPG difference but I could feel the difference in torque during acceleration. Once I switched to Top Tier(which was very shortly after I went through 3-4 tanks of gas), the difference was not as noticeable. Could it be you went from non top tier to a top tier fuel?
 

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Discussion Starter · #16 ·
I always use top tier gas exclusively. Went for another drive yesterday of about 200 miles to the coast. Filled with 87 octane top tier. Mix of 60mph driving and dawdling around in National Park and "tourist towns". 31,8 mpg shown for the trip - 31.67 by hand calculation. Car ran great. I have run this same route many times before and had another surprising observation yesterday. One section has a series of long hills and I found that the car pulled 55 to 60 mph in 6th gear up these hills more easily than before. Before I usually ended up downshifting to 5th to maintain speed without needing a lot more throttle. The engine just felt "happier" with a downshift when I was running premium.........but not yesterday. I have changed absolutely nothing on the car except fuel and it was a typical 80 degree day.

I know this is counter to what is often reported regarding fuel selection, but I can't deny what I've observed with my car and I pay pretty close attention to how things run. Since my initial post on this subject I've run it up through the gears at full throttle a few times. Absent any actual measurements, I guess I am convinced by "seat of the pants" that the car has slightly more top end power with premium (as it should) but only after running through a few gears. For just ordinary driving at less than max power or a quick burst running up through just one gear, my car seems to run every bit as good on 87 octane though, so that's what I will use.

A couple other thoughts: 1) I don't live in the "sticks" but neither is it a populous area - I've often wondered how long premium fuel sits in the tanks before being pumped, i.e., how fresh it is and if it really is at advertised octane. WAY higher use of 87 around here. 2) My car has an aftermarket intercooler and I run 1 heat range cooler pregapped plugs - could this help delay retardation of timing on the stock tune when asking for a bit more power (not WOT) such as climbing hills etc. as mentioned above?

Anyway, thanks for indulging - I appreciate everyone's comments and feedback!
 

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Interesting thought in how old premium gas may be. I just finally used up the 87 the dealer put in my 鈥21 HPP and fill it with 93 on a day trip @(5.79/gal!!)鈥80 cents a gal more than 87. So it may be in that underground tank a lot longer these days. I鈥檝e never seen that high a delta but it was a Highway service area and the low fuel light on so鈥..
I got 28.2 mpg on that trip of 50 or miles to the pump and reset at the pump. We hit heavy stop n go traffic and it did include a few hard acceleration stunts when possible. On way home with some around town traffic, some highway traffic but not as heavy and several wot runs I got 29.3. My calibrated butt Dyno 馃槅 indicated a noticeable improvement in power vs 87. Nothing scientific but I can get 93 for a far smaller delta around home and it鈥檚 not a daily driver so that鈥檚 what it will be drinking.
 

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I always use top tier gas exclusively.
Top Tier gas isn't going to have any measurable impact on your mileage. The added detergents that make Top Tier Top Tier may over a long period of time keep your mileage from degrading do to deposit buildup. If anything you would get worse mileage with Top Tier because there is going to be less gasoline in a gallon of fuel because the higher concentration of detergents.

FWIW, I buy about 90% of my gasoline at a local convenience store chain which does not sell Top Tier and have never had an issue with deposits in close to a million miles of driving. Also, I have never seen a measurable difference in mileage between E10 87 and E10 93.

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I am rather skeptical of the top tier thing, at least here in Canada. The largest sellers in Canada are Esso/Mobil (2000+ locations), Shell (1300+ locations) and Petro Canada (1100+ locations). Of these, only Shell is top tier. While Exxon is top tier in the US, I suspect they simply didn鈥檛 want to pay the piper in Canada, as let鈥檚 face it, top tier is a licensing act, so you鈥檙e paying for the privilege. I don鈥檛 imagine that Esso/Mobil is selling crappy gas here, and that is what has been going in our cars for years. I used to use Shell but switched when a Mobil station opened at the supermarket we frequent, it was simply more convenient and then became habit.
 

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Top Tier gas isn't going to have any measurable impact on your mileage. The added detergents that make Top Tier Top Tier may over a long period of time keep your mileage from degrading do to deposit buildup. If anything you would get worse mileage with Top Tier because there is going to be less gasoline in a gallon of fuel because the higher concentration of detergents.

FWIW, I buy about 90% of my gasoline at a local convenience store chain which does not sell Top Tier and have never had an issue with deposits in close to a million miles of driving. Also, I have never seen a measurable difference in mileage between E10 87 and E10 93.

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And Costco sells Techron by the case.
 
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