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I drive a 2015 iGT HB for a daily and it's working out for my commute. A bit boring at times due to having an automatic tranny but when you need someone else to drive the car back home for the bar, there's no worries about the DD not being able to drive stick. I've been getting good MPG on my 40min commute to work but for a couple of weeks now I have experienced my car struggling up hills forcing downshifts and resulting in an annoying jolt. So 2 days ago I started to put premium gas in my car. With extra octane the car feels a bit more powerful coming off the line, no struggles going up hill, and accelerate much quicker. I just filled up my tank and now I can not go back to regular gas. Due to the gas prices being low, its not much of an issue with a price difference of $5 but I can see it being an issues if gas prices were to go back up to justify the purchase. Has anyone gone through the same issues?
 

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I doubt there's much difference in performance/mpg with premium gas on our cars. I've switched to 91 oct a couple times and didn't notice any difference. I will say that there are days the car will run really well and days where it'll feel sluggish. When the weather is cooler and a bit humidity in the air, the car runs very well and seems to accelerate much quicker. When the weather is warmer it sometimes feels more sluggish overall, and not as smooth. It's just what I've observed and all this was with regular 87 oct gas.
 

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Placebo affect. Just switching octane won't net you any performance gains. Your ECU/ignition timing has to be tuned for the appropriate fuel to actually see a difference.
 

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I own a 2012 sky and I did notice a diffence from going from 87 to 89 octane. The engine runs smoother. I think that the fact that the pierzo microphone is not hearing spark knock at WOT at the same A/F mix tells the computer to adjust spark timing. I'm starting to think that the timing is set to run lean from factory on 87 octane and when a higher octane is used the timing is then adjusted by the ECU. Not feeling any extra power or torque though. If it's there it's very minimal. As stated, cold air being denser will change the A/F and does make the car feel more powerfull vs hot days. I made a port hole in one of my old cars air filter box for that reason. I capped it in the sum er and winter I would let the breather take in some engine heat. Saved on fuel, engine ran warm quicker, got heat in the cabin quicker. GM had that sort of trickery in their cars in the past that was controlled by an electronic valve.

Another possible factor is accidently adding fuel with less or no ethanol in it vs 10% ethanol thatnwas previously in your tank. Pure gasoline explodes a little more from what I had read. Again, this is probably because of the factory tune.
 

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Placebo affect. Just switching octane won't net you any performance gains. Your ECU/ignition timing has to be tuned for the appropriate fuel to actually see a difference.
i thought part of skyactiv was that it was always detecting knock and trying to adjust timing right up to before it knocks

i thought skyactiv with premium could use diff timing (ecu auto adjusts for it) and potentially make more power

is that not the case?
 

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i thought part of skyactiv was that it was always detecting knock and trying to adjust timing right up to before it knocks

i thought skyactiv with premium could use diff timing (ecu auto adjusts for it) and potentially make more power

is that not the case?
yes this may be the case. this type of adjustment was reserved for luxury/high end cars in the past, but its starting to trickle down. ECU uses the knock sensor to continually adjust the ignition timing...its a matter of how safe the ECU is going to play it. if its staying within very safe limits, fueling up with premium might not do much. little more aggressive and it could start to advance the timing a bit.

the difference in fuel economy/power isn't going to be much either way. i've tried premium in my mz3 and so far i've noted no difference. worse fuel economy if anything.
 

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The SkyActive engine has a lot of tech to reach high compression ratios, so by using premium gas you help the engine to avoid premature detonatios which is a problem with this engines and the reason why are equiped with 4-2-1 exhaust.

So I would stay with premium but the ECU can perfectly handle regular gas.
 

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It's all placebo effect. Unless someone wants to pay for a dyno test and prove otherwise. With gas prices so low, the last couple times I filled up, I thought I would see if there was any difference between premium and regular gas for mileage. Mainly for giggles and grins. My average MPGs are showing .3 higher 1/4 way through my second tank. However, even with regular gas, it's not surprising to be up around 34 MPGs halfway through a new tank of gas. It's all about that morning traffic. So, to me, it definitely looks like it's all placebo effect.
 

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Discussion Starter #12
It may be the placebo effect and it has been cold quite a bit maybe the emission recall maybe the issue. I really do not mind pay 5 more bucks extra for a full tank of premium.
 

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It really depends on my driving. If I'm going all over california like I normally do. Premium. If I'm driving across the salt flats, regular.
 

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Yup....we can all use this as placebo, too.....cheaper than premium.:)
The difference for me is about 1.2mpg for mileage with premium. I might be different because I'm always lugging the engine up one hill or another with 200-500lbs worth of gear. Just the nature of driving in CA. Yes, it runs on 87, but my experience with it on 87 has never been positive. My main issues revolve around just starting up, and especially when it's cold it will stumble on regular. I work in sales so I'm usually starting and stopping pretty regularly and I have a pretty regular route. In regards to power the same hill will require me to drop down to 4th to stay at 65mph than 5th.

The engineers may have designed it to run on regular, but the way it uses it's knock sensor to change the timing it will see a gain under many conditions with premium fuel.

-Kevin
 

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i thought part of skyactiv was that it was always detecting knock and trying to adjust timing right up to before it knocks

i thought skyactiv with premium could use diff timing (ecu auto adjusts for it) and potentially make more power

is that not the case?
I can confirm it is the case.

Dave
 
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