Best MPG in Si

My best mileage so far was about 37 mpg driving a consistent 40-45 mph on the highway in a snow storm a few months ago. I've since figured out from the forum that that it was probably closer to 34-35 mpg (I've checked the computer against doing the calculation myself since then) but I'm still mighty pleased.

Generally, I'm getting about 30-31 mpg doing my daily, mixed stop-and-go commute with some infrequent vtec'ing (again, doing the math myself--the computer says 32-34 mpg). Still mighty pleased since that's what I'm getting with the old economy car that isn't nearly as much fun to drive.
 
The hot weather and running AC all the time has brought my MPG way down to around 29-30. But that's still pretty good for this car/engine combo.
 
I don't give a SH*t about how efficient my Si runs. First of all I keep slammin my foot down cuz I like the way it feels and I love the sound the engine makes even though it's stock. I'm never going to win the best gas mileage contest nor do I want to. I drive my car the way it was supposed to be driven.
 
bootyluvr said:
Exactly! People who care about MPGs should have bought a LX or EX!! Well said. I could care less what my MPG's are.. Didn't buy the car for that. Does one buy an Si for awesome MPGs? :confused:
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turbojay said:
Why spend $25k on a car and then worry about few cents for premium gas. Just buy the lx or ex instead.
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I see I'm not the only one that thinks like this. :ohsnap:
 
turbojay said:
The last tank of gas got me the best mileage yet. Nav computer put the mpg at 37.4 but actual math put it at 35.7. 404.4 miles divided by 11.3 gallons at fill-up. The drive was a mix 70/30 highway/local. Drove right at 55 mph on highway and coasted to traffic lights to avoid stopping.

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I am here: http://tapatalk.com/map.php?pyy52y
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nice!!! those r impressive.. wish i could get there but i cant resist i gotta hit vtec.. best i ever had was 31mpg with 310miles a tank
 
It's hard to have it both ways: When the computer retards the engine to compensate for 87 octane, your MPG should go down as well, even if it's only 1 or 2 MPG. I'll confirm this with Honda next week. But I agree with those who live half their lives idling in traffic... by using 87 you can save enough for your next down payment, and (per the owners manual) you will NOT harm the engine unless you use gas that's LESS than 87.

Personally I don't drive much so I use 91. For those in Canada or Europe where it's outrageous expensive you might consider filling with half with 87 and half with 93 (averaging 90) and coming very close to the recommended octane of 91.
In the summer of 2012, I recommend enjoy $3.50/gallon while you can!
 
bootyluvr said:
Exactly! People who care about MPGs should have bought a LX or EX!! Well said. I could care less what my MPG's are.. Didn't buy the car for that. Does one buy an Si for awesome MPGs? :confused:
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you've got a good point, booty.... i'm with ya. Still, some appreciate the car's split personality. It can be a mild mannered reporter from the Daily Planet, or it can jump into a phone booth revealing a big red "S" for Superman... or in this case "SI".
 
Bruce Bartlow said:
you've got a good point, booty.... i'm with ya. Still, some appreciate the car's split personality. It can be a mild mannered reporter from the Daily Planet, or it can jump into a phone booth revealing a big red "S" for Superman... or in this case "SI".
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Yeah its good it can be the best of both worlds but I hope people that buy an Si don't think they will get LX or EX MPGs.. lol they want to have more fun in it because it has the powar! ;)
 
Where I'm at (Nova Scotia) we have three grades - Regular, Mid & Supreme with octane ratings of 87, 89 and 91 respectively. The prices this week are as follows (excuse the metric measurements) - Reg: $1.26.7/L; Mid: $131.2/L; Sup: $1.34.6. The fuel tank capacity in the SI is 50L. So then by my calculations a full tank of each costs - Reg: (1.267*50)=$63.35; Mid: (1.312*50)=$65.60; Sup: (1.346*50)=$67.3

Now if $3.95 is going to ruin your day... well all the power to you, stick with regular grade. Personally I'll take the supreme "penalty" since I'd prefer the peace of mind of knowing that I'm putting the gasoline into the engine that Honda intended.

This is the same as people going batshi* crazy when the price of gas goes up by 2 or 3 cents. The difference is negligable unless you're filling up a truck on a weekly basis. Of course over the long term the difference can increase, but gas prices are extremely unpredictable so I think it's unfair to do long term estimates and theories.

I agree with the rest, if MPGs are your concern then buy a non-SI model, but to each their own.
 
Before you get all excited about all this money savings buying cheap gas, you should compare the MPG between the two. Most vehicles that ask for 91 get worse MPG when fed regular, some lose a lot. High compression engines can ping depending on engine tuning even at light throttle so that argument doesn't always apply. Neither does the low temp one given lower temp = higher air density = more cylinder pressure. You have made a lot of assumptions here talking yourself into not using 91+ octane gas.

Also understand that running 87 requires the engine to retard the ignition timing which creates more heat in the exhaust system, makes the cat and the exhaust valves run hotter etc. ANY detonation at all beats up the rod bearings and ring lands on the pistons. All it would take is a burned up cat to negate most of these -assumed- savings + you have neutered this high performance car you bought by using the cheap gas. Break a piston ring/land or spin a rod bearing and you just blew 4-5k+ in repairs. Like others said, if you are concerned about cost of fuel/operation (like I was and was the reason I got an LX) why would you buy an si? If it was mainly to look cool, put si badges and stickers on an LX and save 5K on purchase price AND get better MPG :P

I am always shocked when owners of all sorts of high performance cars (cars like si civic or turbo cars) insist on using cheap gas in them.. I've worked at repairs shops for most of my life as a service writer and have seen the damage over time that long term use of low octance gas does to high performance cars. The owners manual is right in stating it is not required and won't damage the engine in an emergency (you are out of fuel in the boonies and all they have is 87) but regular use isn't recommended for a reason. You seem to be totally ignoring this sentence in the manual " Use of a gasoline with a pump octane less than 87 can lead to engine damage." It's the same as using cheap oil filters, why risk ruining an engine doing this?
 
Stephey said:
Before you get all excited about all this money savings buying cheap gas, you should compare the MPG between the two. Most vehicles that ask for 91 get worse MPG when fed regular, some lose a lot. High compression engines can ping depending on engine tuning even at light throttle so that argument doesn't always apply. Neither does the low temp one given lower temp = higher air density = more cylinder pressure. You have made a lot of assumptions here talking yourself into not using 91+ octane gas.

Also understand that running 87 requires the engine to retard the ignition timing which creates more heat in the exhaust system, makes the cat and the exhaust valves run hotter etc. ANY detonation at all beats up the rod bearings and ring lands on the pistons. All it would take is a burned up cat to negate most of these -assumed- savings + you have neutered this high performance car you bought by using the cheap gas. Break a piston ring/land or spin a rod bearing and you just blew 4-5k+ in repairs. Like others said, if you are concerned about cost of fuel/operation (like I was and was the reason I got an LX) why would you buy an si? If it was mainly to look cool, put si badges and stickers on an LX and save 5K on purchase price AND get better MPG :P

I am always shocked when owners of all sorts of high performance cars (cars like si civic or turbo cars) insist on using cheap gas in them.. I've worked at repairs shops for most of my life as a service writer and have seen the damage over time that long term use of low octance gas does to high performance cars. The owners manual is right in stating it is not required and won't damage the engine in an emergency (you are out of fuel in the boonies and all they have is 87) but regular use isn't recommended for a reason. You seem to be totally ignoring this sentence in the manual " Use of a gasoline with a pump octane less than 87 can lead to engine damage." It's the same as using cheap oil filters, why risk ruining an engine doing this?
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Excellent explanation Stephey!
 
BTW the math on 100K miles @30MPG you save ~$800 by using 87 rather than 93. For the average driver of 15K a year that = ~120 a year. And that assumes there is no MPG improvement from the better gas.
 
bootyluvr said:
Yeah its good it can be the best of both worlds but I hope people that buy an Si don't think they will get LX or EX MPGs.. lol they want to have more fun in it because it has the powar! ;)
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Speaking of gas mileage, when there was no speed limit in Montana I drove my 1991 5 - speed Accord EX with W.O.T. (or almost) nearly all day long, averaging 110 MPH for 10 hours. It was glorious. Top speed was 132, pegged +, thanks in the part to a very low friction synthetic oil I was using (Amsoil Series 2000, used by Bobby Unser and others in the F1 circuit) At that point, over 125 that is, the front end was getting light so I backed off to 120MPH and eventually to a snails pace -- 100MPH -- around the cities.

Now most people would say my 13MPG that day really sucked. I say it rocked. You can't put a price on that kind of experience.
 
Stephey said:
BTW the math on 100K miles @30MPG you save ~$800 by using 87 rather than 93. For the average driver of 15K a year that = ~120 a year. And that assumes there is no MPG improvement from the better gas.
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Hey nice work! I'll be asking Honda about the ECU changing the ignition timing with regular fuel. At this point i'm thinking premium might well give us slightly better mileage, like one or two/mpg max. Still, $10.00/month -- even for heavy drivers at 15k/yr-- isn't bad at all. Thanks for the numbers!
 
Freddiii said:
Got 39 mpg on my way home from Bridgeport. Went down to 36 wen I got into Brooklyn.
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My '09 Accord with a very similar 2.4 engine gets 31/32 consistently in freeway driving. Because the SI is so much lighter it should get better gas mileage than the heavier Accord. At least when you want it to! :party:
 
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