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Super happy with my GT, just wondering what gas are other GT owners filling up with?
and what mileage you guys are getting. I was thinking of at least putting mid grade like 89 or even 91
 

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Wow you are asking for an ear full on this one...

BLUF : Where you buy it is more important than what you buy when discussing fuel with the 2.5T.

They aren't kidding around when they tell you to use TopTier fuel in the manual. Homepage

A couple of us myself included have experienced some misfire issues on non TopTier fuel.

I honestly get my best mileage on 87 and currently my GT is bone stock. I also always use my one allowed can of TECHRON fuel system cleaner about 2k out from oil change time.

I am sure others on here will discuss tunes and higher octane benefits etc. I can only say that my best highway mileage runs have come on TopTier 87 Octane fuel, ambient temperatures in the mid 70s, and humidity above 60% at about 700' above sea level.
 

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2021 Kia K5 GT
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Kia recommends 87 OR higher. I use shell 91 and get 10.5 L/100km mixed. Many also put Costco but I'm not sure if they use top tier.
 

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Costco is said to have top tier. I have used costco gas a few times with no issue but since installing the JB4 I only use shell or chev 91. I get an average of 22-25 for the most part. i do not drive gentle though :)
 

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I've been thinking of trying out Petro Canada ultra 94 but has ethanol and some say they get lower mileage. So, I may try using boostane with shell 91 and try to boost it to 93 octane and see if there's a difference.
The only way we can tell is if we data log.
Get logs with 91 octane and logs with 93+ octane. There we will see if our ecu is pulling timing or not with either or. Maybe @RuffGT can data log 😉
 

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The AAA app shows local top tier fuel availability. You don’t need an account to view local gas prices. It’s been very helpful.
 

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Use 87 and only use gas at Esso or Shell, getting about 10.1L/100km on both highway and local road (mid-town Toronto)
 

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I've been thinking of trying out Petro Canada ultra 94 but has ethanol and some say they get lower mileage. So, I may try using boostane with shell 91 and try to boost it to 93 octane and see if there's a difference.
The only way we can tell is if we data log.
Get logs with 91 octane and logs with 93+ octane. There we will see if our ecu is pulling timing or not with either or. Maybe @RuffGT can data log 😉
Am I the only one here with a tuner lol.. we do not have 93 here and I am not going to mix.. I’m lazy. I can get 91 and 100.. also remember my spark plugs are different And I do not buy gas or drive in a way to get better mileage 😉 But for you @1st K5 .. I will get some logs
 

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Am I the only one here with a tuner lol.. we do not have 93 here and I am not going to mix.. I’m lazy. I can get 91 and 100.. also remember my spark plugs are different And I do not buy gas or drive in a way to get better mileage 😉 But for you @1st K5 .. I will get some logs
LOL... What plugs are you running? With jb4 set at map 0, would like to see fuel trims using 87 and 91. I'm more curious for performance gains.
 

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LOL... What plugs are you running? With jb4 set at map 0, would like to see fuel trims using 87 and 91. I'm more curious for performance gains.
Still running the HKS XL 45s... I am also getting it Dyno’d this weekend or next so you can see some real numbers. I will try and get the logs for ya.
 
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