In the manual it says that the recommended octane to use is 91, but around my area that is very hard to find-they either have lower (87) or higher (93)...i have been using 93 and my gas mileage has been poor. Is this because of the higher octane? I know some cars perform better the higher the octane, but the manual says to run it on 91. Is that the reason my gas mileage has been so poor?-because I baby my car except for one or two times where I'll stretch it per tank

 

I use 93 and notice horrible gas mileage when in the city. On the freeway it was much better. When I got to DC though I disconnected the battery and did a 3rd gear pull to redline. I don't know if it helped but from what I heard a couple of pulls makes the computer adjust.

 

higher is better. the manual recommends 91 because the poor guys in cali can only get 91, so dcx can't recommend 93 because of them. higher is better.

what are you calling bad gas mileage?

 

92 octane and mileage is okay not that i tried anything less

 

the last time i filled up i had 162 miles...and like i mean most of them are city goin to and from schooL, but i thought that maybe the octane had somethin to do wth it

 

The PCM is calibrated to run on 91. Using a higher octane fuel is not necessary. You can use a higher octane but be aware that the higher the octane the more stable the fuel is and less volitile. I have seen tests where a car actually losses HP when using a higher than necessary octane fuel. Bigger is not always better.

 

I think it is more your driving than it is the octane causing you milage problems. I also use 93 and if i drive it nice on he highway, I get 280 to 290 miles. If I drive like a maniac i get 200 and below. I know it is very hard to stay out of boost. It is very addicting, but it kills your milage. just my $0.02

 

in this case it is. the ecu is not calibrated for 91 octane. it will accept it because it has to, but more often than not those using 91 are getting a lot of knock and are seeing differences in power. these cars run much much better on 93 than they do on 91.

 

Just like PSI said, at the highest we can only run 91 here in Cali. That is what I have ran in the car since we got it in September. I get any where from 18-24 on a mixture of town and freeway driving. When I am strictly freeway I get really great 22 to 29. Depending on where I want to keep my lead foot. Honestly though, I've only gotten 29 on really loooooooong trips. Where I've been on the freeway for straight shot hours at a time running 80 constantly with no stop and go. I love the car. I didn't expect to get 30 or 40 something MPG, because it's a sports car, and well, you just can't expect it.

11 more days and my baby will be home from IRAQ guys... YAY YAY YAY YAY YAY X's infinity...

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It beats my 03 Ram's 13 MPG that I traded for my SRT