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Discussion Starter #1
Greetings All,
I recently purchased a 2015 Si Coupe with 46k miles
I noticed that my gas has been going down much faster than I feel it should be. I filled up a fill tank of 91 octane and the fuel economy shows that I have been driving at about 28 MPG and my commute to school is 22 miles total round trip. Just 2 days after I filled up, my gas is reading half a tank. I just want and idea of where the problem could be and if it is or isn’t normal.
Thanks


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Has your driving style changed? Are you hitting more traffic? Those affect mpg the most. I found cruise control at 65 for all highway I can get 34 mpg hand calculated


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Try driving like there's an egg under the accelerator pedal. I get 33-34 in all town driving and can get 43 on all highway without trying too hard. The R18 is a great engine ; )
 

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Greetings All,
I recently purchased a 2015 Si Coupe with 46k miles
I noticed that my gas has been going down much faster than I feel it should be. I filled up a fill tank of 91 octane and the fuel economy shows that I have been driving at about 28 MPG and my commute to school is 22 miles total round trip. Just 2 days after I filled up, my gas is reading half a tank. I just want and idea of where the problem could be and if it is or isn’t normal.
Thanks
Hello and welcome.

You say you recently got the car, so you have limited basis for comparison?

28 mpg is a reasonable figure for an Si. My R18 gets about that but my commute (33 miles each way) is a choker - a lot of heavy traffic - and then when it opens up I often hammer it until I get up to speed.

If you want more mpg, try some of the suggestions mentioned above.
 

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Your fuel economy can vary depending on several factors, including traffic, temperature, and driver habits. 28mpg doesn’t sound unreasonable, but we would need more information. Check your tire pressure as that can make a big difference also.


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Your fuel economy can vary depending on several factors, including traffic, temperature, and driver habits. 28mpg doesn’t sound unreasonable, but we would need more information. Check your tire pressure as that can make a big difference also.


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He's right. 2# tire pressure difference makes a significance in my car, and is especially noticeable on a long highway trip.
 

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Greetings All,
I recently purchased a 2015 Si Coupe with 46k miles
I noticed that my gas has been going down much faster than I feel it should be. I filled up a fill tank of 91 octane and the fuel economy shows that I have been driving at about 28 MPG and my commute to school is 22 miles total round trip. Just 2 days after I filled up, my gas is reading half a tank. I just want and idea of where the problem could be and if it is or isn’t normal.
Thanks
For clarity, are you saying that after 44 miles your fuel gauge went from full to half-full? Otherwise 28mpg isn't bad for the K24, in my limited experience.
 

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For clarity, are you saying that after 44 miles your fuel gauge went from full to half-full? Otherwise 28mpg isn't bad for the K24, in my limited experience.
I'm curious on that as well. Like several people have stated. 28 for the si is not bad. I think I stay around 26
 

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Try driving like there's an egg under the accelerator pedal. I get 33-34 in all town driving and can get 43 on all highway without trying too hard. The R18 is a great engine ; )
I can get the same or better with my K24. I drive with the idea that every time i use the brakes, i waste gas. It also explain why i did my first brake job at 200k km. (+ or - 125k miles) I also don't drive that fast anymore. A couple of expensive speed tickets did the trick for me.

To OP. Did you do a Tune Up to your car, are the brake dragging, alignement..?

Marko!
 

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Discussion Starter #14
I can get the same or better with my K24. I drive with the idea that every time i use the brakes, i waste gas. It also explain why i did my first brake job at 200k km. (+ or - 125k miles) I also don't drive that fast anymore. A couple of expensive speed tickets did the trick for me.

To OP. Did you do a Tune Up to your car, are the brake dragging, alignement..?

Marko!
The car came from the dealership and is certified used. brakes are good, alignment is good, don’t know if a tune up was don’t recently. The tire pressure is at 35 psi. Right now outside temperature is between 50-70 degrees F. I don’t drive the car hard and almost all of the miles I drive are freeway/highway with basically no traffic. There may not be anything wrong with the car I’m just asking bc I have a 2005 Hyundai tiburon GT (2.7 L v6) that is rated for lower Mpg but my fuel last longer than my si with the same driving route and its kinda frustrating.


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Yeah the small gas tank doesn’t help
<coffee out the nose> haha

Yeah, OP, I have to ask, do you know the capacities of both cars' fuel tanks?

Never mind, I looked it up.

2015 Honda Civic Si coupe - 13.2

2005 Hyundai Tiburon GT - 14.5

Gee, do ya think 1.3 gallons of capacity would make a difference in how long the fuel lasts?

Btw, what was your average mpg in the Hyundai?

Without actual numbers this whole thing is pointless.
 

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<coffee out the nose> haha

Yeah, OP, I have to ask, do you know the capacities of both cars' fuel tanks?

Never mind, I looked it up.

2015 Honda Civic Si coupe - 13.2

2005 Hyundai Tiburon GT - 14.5

Gee, do ya think 1.3 gallons of capacity would make a difference in how long the fuel lasts?

Btw, what was your average mpg in the Hyundai?

Without actual numbers this whole thing is pointless.
Our tank is 13.2? I get the light and no dashes and I fill up with 11 gallons.


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Our tank is 13.2? I get the light and no dashes and I fill up with 11 gallons.


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I've ran it on the light for like 2 days before and still only put like 11.5. I have not once filled up a full 13. Had a 99 civic that would do the same thing. Light would be on for days, never put more than 10 gallons in.
 
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