OK, this is going to sound weird, but I have put 2 tanks of 92 in my car...you can see my mods down below...I have Injen CAI, full exhaust....I drive an auto.

I don't drive any differently, I'm not claiming it feels like I have any more or less power, I'm just stating that driving the exact same as I always do, my car appears to be getting about 2 MPG's better with higher octane fuel.

I have always used 87 because I know there is no point in higher octane on an non-tuned car...I started using 92 in preparation of my Trifecta Tune that I just ordered.

I have a heavy foot and I do a lot of in town driving right now because I have a full-time job that is only ~15 miles one way (half and half highway/city) and a part-time job delivering pizza in town here.

I only average 22 MPG because of my driving habits normally. I've been getting about 24 MPG now for the past 2 weeks that I've been on 92. I haven't taken any highway trips lately on the 92, but on normal 87, I average about 35-37 MPG doing ~70 MPH.

I am not sure what is going on, but I just thought I would bring it up and see what others have to say.

I'm going to be doing my tune with MPG's in mind and hope to see an increase, but I may have to adjust my driving habits to really see a difference. I'm not going to say I won't be happy to have some extra power as well.


EDIT: I'm sure the question will come up, but I check according to my DIC AND according to doing the math (total miles divided by gallons consumed)...they are both about the same.

 

note the ethanol content, 92 may not have ethanol but all 87 does have 10% now in just about every state, give it a look on the pump, should say on there if the fuel has ethanol, your difference is likely the lack of alcohol which is a less dense fuel per gallon and at 2 mpg, that sounds about on the money for 10% E.

 

Thanks for that info...didn't even occur to me. I will check that next time I go to the station to fill up.

 

hmmmm I did the same thing in my old LT auto, i did not see a diffrence though, but on that car and my G5 the DIC has always been minus 2 on my mpg (as in my DIC will say 24 and my real mpg is 26)

 

Mine is fairly accurate...it usually only a +/- 0.3 MPG difference from one to the other.

 

The difference might be in the burning of the gas. 92 octane is put in higher compression, higher horsepower vehicles because it takes longer to burn so it decreases engine temperatures in those vehicles. Maybe since its a higher octane and its taking longer to burn you actually are traveling farther before the same amount of gas that would normally be burned is burned due to the higher octane. Just a thought. This is the first time I have ever owned a four banger and I also own an 04 cobra with a kenne bell and higher octane is vital for those types of cars.

 

I was under the impression that all gas in MN has 10% ethanol. Most of the pumps that I fill up at don't even display the amount of ethanol. Occasionally in Wisconsin, I see some pumps have a no-ethanol premium (I think they call it non-oxygenated or something like that). I usually fill up at those pumps when I can.

 

depends where you go..... and the station "at least in canada"
Sunoco Gold 94 - has 10% ethanol
Shell V-Power 91 - has 0% ethonal

 

No it doesnt.


You didnt mention if the fuel was from the same station or was the same brand, etc..... Both of those things will affect mileage, also many brands put their highest detergent and other additive concentrates into their higher octane fuels this can affect mileage as well. (for example, not only does Shell Vpower have higher octane than regualr it also has more of the Nitrogen/etc cleaning compounds)

 

I fill up at Super America, Shell, BP, Holiday, and other stations (I will fill up wherever there is a station when I decide I need fuel)...the couple tanks of 92 I put in were from Shell, the last tank I put in was 93 from BP.

 

Well switching from an "average" 87 octane fuel to a Top Tier 92 octane fuel like Shell will almost always yield improvements in mileage.

 

I got my Trifecta tune installed tonight and did some driving on the highway and city roads....yay! Even better fuel economy now...trouble is that the tranny shifts so nicely now and I can feel a little extra power (nice powerband for sure now) so hopefully I keep off the accelerator enough to see the MPG improvements. Time will tell tomorrow when I deliver pizza again.

Datalogged and sent that off tonight, we'll see if any tweaking is needed.

I wanna take a highway trip and see if I'll actually hit 40+ MPG's now. Hopefully over 40 if I'm driving 65 because I did high 30's at 70-75 with an un-tuned car.

 

This is basic logic, 87 octanes = less stable and pre-ignite from the heat of the engine, 91+ is more stable and does not do that wasting less gas.

 

I usually buy Sunoco Premium Plus (93) and I honestly did see a difference in gas mileage by about 2. I use that gas regardless of gas mileage increase only because it burns cleaner and is better for the engine. Everyone can try and tell me that I am wrong, but every time, and there has been no exceptions, when I go back to regular 89 I see a decrease of about 2 mpg, and then when I go back to premium plus I get the mileage I had before. This is in NY as well. My driving habits don't change, and I drive mostly highway. I also have a CAI and a Cat-back.

 

I had a big milage jump. I got an alignment, made sure all tires were propper psi, change intake filter to gmpp (I was washing my other filter and accidently ran it over when I was letting it dry lol oops) cleaned TB, and I use sunoco 91. I guess from cooler weather in addition, and my jet chip stage 2 I got a 2.7 mpg increase (by math rather than dic) I was rather impressed. 26.7 mpg 95% city 5% highway. Now that's awesome. 160 miles till half tank. And I didn't really hypermill to much either. I shift at 3k

 

Here is the Facts on Ethanol Content, for Western Canada/Pacific North West, There are two types of gas made, regular 87 and supreme 92 (chevron has supreme+94 octane) They are all blended at the pump. Regular Blendstock is now made to 82 octane and then is spiked with ethanol to bring it up to 87. This may explain why mpgs have went down over the past couple years as the ethanol has less energy, as well as its octane boosting properties allow worse gas to meet specs.

87 = 10% ethanol

89 = 7% ethanol

92 =2% ethanol

94 = 0% ethanol

The stuff in supreme gas is totally different in makeup then in regular, a good portion of supreme is a product called isooctane. its cool stuff!

 

Its interesting that I have had almost the exact opposite. I stopped putting 93 in the tank when it hit $4/gal and started putting 87 in instead. My car is supercharged and it doesn't pull as hard on the low grade gas (which I expected) but it seems to idle smoother and it gets better MPG. This makes no sense to me. Anyone have any ideas?

 

Are you tuned? Is the tune good? lol, sorry, but that's the only thing I can think of. I really have no clue why this would be.

 

I run my TA on 93 cause the cam tune and timing need the high octane or you can hear the pre detonation , I run my Turbo SS on it as well since my turbo talon always ran better on premium. Lower octane fuel burn faster so logically you should get less mpgs. Higher octane is needed in tuned cars usually because of advanced timing and but if you run a blown car with stock tune and even more so a colder plug the lower octane will burn like higher octane with a hotter plug. Long as you don't get and pre detonation at wot with 87 then your fine I have run my cobalt on 91 and 93 with no noticeable difference in power or not with Mobil gas. I did notice a gain when I installed the new plugs that a one range colder.