Si gas mileage getting worse...

[jsnymeyer]

I don't want to hear any of you b*tch, lol. I've only been getting about 200 per tank/19 mpg lately. That's with a CAI, too. I think I have it the worst

[redclown]

I got 280 first tank with 3 or 4 bars and second fillup was 315 with 3 bars! It was mostly highway though at around 58-63mph!

[2likru]

I must be lucky becouse I got 400 miles out of my tank the last trip I took. btw my car dosnt have the wing and has a cai.

[Implosive_Disgorgence]

270-290 a tank here. mostly city driving with atleast 1 trip to vtec everytime i take the car out, but usually more vtec. i lovez it.

[chugiboi]

i went from 490-500 miles per tank to 360 miles per tank with the A/C on 100% of the time in my 08 Civic Hybrid.

[Whocares05050]

Ive been getting worse. i usually get 310 till fill up, now its more like 260

[OEM_SI]

I use the cheap 87 octane gas and get 300 MPT.

[Whocares05050]

Originally Posted by OEM_SI

I use the cheap 87 octane gas and get 300 MPT.

I sure hope not in an SI

[whizy]

mine is 31.6 to 32mpg (80 miles everyday half hwy half city) not much traffic bcoz I travel 6am & return 2pm

btw .. it is 08 Si with Premuim gas 91 octane

[bmnorm2]

why would ethanol make your fuel economy drop? Ethanol is higher octane... you actually get more horses from your engine with E85 (85% Eth, 15% Petrol) then you do with 93. That is of course if your engine can take the E85

[Hockeyman8282]

damn i get around 200 miles per tank. your lucky!

[nayilsi]

Try

1. Setting the correct tire Psi
2. Mobil 1

[nayilsi]

Originally Posted by datbacker59

300 to 350 mpg? wtf!!! im getting 260-290

lol I got 398 with 2 bars..... with the 3rd bar just disappering

98% hwy using only CC..... outside temp was approx 42-48 deg F

[RobertsD]

Originally Posted by bmnorm2

why would ethanol make your fuel economy drop? Ethanol is higher octane... you actually get more horses from your engine with E85 (85% Eth, 15% Petrol) then you do with 93. That is of course if your engine can take the E85

Whatever the reason, cars do get worse gas mileage with gas that has for ethonal.

As for me, I get 300+ miles per tank, and it's about 90% city driving.

[BigT]

Originally Posted by bmnorm2

why would ethanol make your fuel economy drop? Ethanol is higher octane... you actually get more horses from your engine with E85 (85% Eth, 15% Petrol) then you do with 93. That is of course if your engine can take the E85

It may have higher octane, but it has a lower energy content. Higher octane can allow you to run higher compression, more advanced timing, etc. This can potentially result in higher power output (if, as you said, your engine is designed for it). However, this doesn't result in more distance per gallon. Ethanol has a lower BTU content per gallon and in most cars will result in lower fuel economy, some more than others.

[edrhee83]

I will say it can be ethanol too. They have 10% ethanol added to gasoline everywhere I go. That can decrease the gas mileage.
I get around 250-260 per tank City.

[nayilsi]

OP do u use synthetic motor oil ?

[Kyle07Si]

Ok, stop stop stop stop.

Guys, alot of things here,

#1 - No GAS gives higher HP and gas mileage, it's just simply not true. An octane rating measures the proportion of isooctane to heptane in a fuel. The fuel's octane rating relates to how much energy it takes to ignite that fuel. It does NOT measure how much power it outputs. That's a old and very well marketed myth that you can thank your gas companies for. If your car as BigT said has a higher compression and REQUIRES premium, then yes if you run it on reg there are going to be differences in power, ect ect.

#2 - If the gasoline says 93 and it's Exxon, and then across the street QuikChek says 93 buy whatever is cheaper. When gasoline arrives at distribution centers, it's all the same. Different gas station chains then buy the raw fuel and add their own blend of detergents. In the past, there might have been more of a difference between different brands of regular unleaded, but these days the EPA requires that all gas contain a minimum amount of detergent to keep car engines clean and running properly. Basically, it's all regulated and they don't let people put in crazy crap that’s going to destroy the environment. All this crap about “use Mobil1” blabla is just marketing. Studies have shown there’s no difference between any of the synthetics that you buy in the store. Unless it’s some race oil, it’s the same stuff.


#3 - How modded are your cars? How fast are you driving? That's going to be a huge % of your gas mileage right there. I get 360 miles to a tank in my Si every time without fail. The difference between 65mpg and 70mpg on the highway is roughly 6% in mileage. Seriously, so at 13.2 gallons, and we will take a rough mean of what I get:

350 miles / 13.2 Gallons = 26.5 miles per gallon avg per tank

Let's take 6% away, that tank just dropped to 329.


Reading through the comments, it seems unlikely that those who are getting lower gas mileage has anything to do with the car but how it is being driven. This tool at work has an 07 as well, just an EX, and he gets something like 475 miles per tank. That's pretty dam good mileage. Try slowing down and not hitting VTEC as much, that's going to make a big difference.

[sofla1984]

I think thats pretty average. Ive got an 07 SI and i drive rather agressively according to my friends and i average about 300-310 per tank putting in about 11.5 gals of 93Oct

[NightFlight]

1. Check your tire pressure.
2. Did they start blending the fuel in your area with ethanol recently?