I had the MPG TSB applied at 19876 miles, and since that time the readout has been very accurate. Sometimes a bit higher than hand-calculated and sometimes a bit lower, but never more than a couple tenths off.

My '09 MT sport now has 30878 miles and has averaged 38.79 MPG. Best tank was 467 miles on 10.3 gal, for 45.34 MPG. I was getting a bit nervous on that one, but I guess I may still have had about .3 gal left

 

My economy is going down hill, first tank 34.73 mpg, 2nd tank 27.45 this tank 26.7 mpg. I'm driving the same places, nothing has changed?? MPG calculated the old fashioned way with paper and pencil.

Average MPG for first 710 mi is 29.58

The meter is telling me around 28.

This is all real short trip (average 5 mi RT ) in town driving with the AC always on and a little bit of idling while waiting. It's been 2 weeks since my last fill up!

I wanted the Soul, but they are reporting 22 mpg around town, so I am still ahead.
JIm 0311

 

You haven't been letting your wife drive it have you? Wives have notoriously heavy feet. I can always tell when my wife's been driving the car because the avg mpg is lower than when I left it. Well, that, and the seat is scooted so far forward I herniate myself trying to get in. How she keeps from slapping the steering wheel when she turns is a mystery.

Otherwise I suspect your first tank wasn't indexed correctly. Maybe you took it on a couple longer honeymoon cruises you don't remember.

27mpg for how you're driving it sounds reasonable.

 

I think 27 mpg for city is spot on. I have noticed it is best not to run the a/c full blast...you can really tell that its consuming more power than the lower settings, naturally. Another thing I found is it seems like it is better to get up to speed as one normally would as opposed to trying to creep up to speed. Where you can make up a little is anticipating your stop ahead of time and coasting into it opposed to gassing it and braking hard. I'm sure you know that. I think that around 27 in town is respectable mpg and to me 32 in city is not even possible.

 

It is also better to run 93 octane opposed to 87. The mileage you will make up running higher octane should pay for itself and its better for your engine.

 

are you trolling me?

93 octane will do nothing for your mileage except lighten your wallet.

 

It's my opinion the $2.50 extra a tank is worth it. I don't mean to get off-topic or start a debate on octane.

 

Probably wise, because (respectfully) you would be wrong.

Cheers.

 

It's not a debate, I'm not wasting my money on higher octane. Have watched the debate and experimented here and there for 46 years. It's a waste of money, does not work.

Right up there with the pyramid shaped magnets that molecular'ly alter the fuel giving astonishing increses in MPG up to 50%. Don't believe me, there are infomercials shown on TV in Asia, proving it!

I played with the AC while watching the meter/graph. I do not drive far so is difficult to do. The major difference with the air on high, low or off happens around 30mph, up to 10mpg according to the meter. Totally unscientific and open to interpretation and mistakes.

At 40mph I noticed little difference in MPG with AC on, off or on low. Will play with this more as time permits.
JIm 0311

 

Heres some History, 1st Regular was always 89 octane and 87 was unleaded. Then the lead came out in the early 90's and it was called mid grade. 2nd the reason your first tank was so high is Honda throws a few gallons of premium ethanol free from the factory because they dont know how long it will sit before its driven, the dealers that drops there own fuel use mid grade or premium because it sits in the tank for a while and it will lose octane and have problems, so your first tank was premium.

Your comment of wasting money was answered by you. If 7 mpg is wasting money then dont use premium. Just think how far 2.40 will take you with regular.

 

It's that doggone ethanol. If you can find 87 octane straight gasoline the mpgs are great.

 

a 25% increase in mpg from a 30% mix of premium/regular. Impressive!

 

Some areas still have 0 ethanol but its hard to find. E10 actually raises the VE volumetric efficiency of the motor by 3.5 percent. The problem is as long as the car is in close loop there is little difference (2 percent)but at loads over 70 percent it goes into open loop and uses 29 percent more fuel. 14.2/11.0=1.29. I have dyno'ed my fit and the fuel air was 14.2 all the way. I use premium and the loads were over 70 percent.

 

Irrefutable proof! JIm 0311

 

The Fit has an adaptive ecu and can adjust itself to benefit from higher octane. Older cars were specific what grade to use and if you deviated you would see no improvement and possibly get worse mpg because those cars couldn't adjust the change in octane. The owners manual to the fit says don't use less than 87 and is not specific to a grade because it is able to adapt.

It will take several drives or several tanks for the ecu to account for the higher grade. Someone that tries to test one tank of 93 against one tank of 87 will not get accurate results because the ecu needs time to adjust.

I am being proactive and keeping a log. I did the switch and I am excluding my first two tanks of 93 to allow the ecu to adjust. I am testing 5 tanks of 87 against five tanks of 93. I think this should be relatively accurate.

At the pump it cost around $40 to fill the tank and 93 is around .25 more than 87. So approximately $2.50 to use premium a tank...$2.50 is a drop in the bucket to run a better gas.

 

score 40mpg for some of you. that rules. I've tried to drive super consistent and nicely with breaking mine in. 1100 miles on it. 4 tanks of gas, each one within 1mpg of each other. peaking out last week at 39.2

(mugen body kit installed) - supposedly improved 1mpg with that but pretty hard to tell. other than the kit, the car at the moment is perfectly stock, oh yes, it's a 5spd manual transmission, not automatic.

 

just wondering, has anyone ever thought of creating a belly pan of sorts (purchased or home made). I saw ONE person online who built their own from super thin aluminum, bolted to the chassis, looked pretty nice. just wondering if that was worth doing if people know. (less drag improving air flow might equate to extra mpg?)

 

cars designed for premium will often retard timing if 93 is not used to prevent predetonation. a vehicle designed to run on 87 won't have to worry about knock running 87 octane. Since 93 has no more explosive power than 87, there will be no difference.

That said, 93 may not contain ethanol which will improve economy.

If you are doing a test to actually compare 87 vs 93, make sure both have the same amount of ethanol, are the same brand, and that you try and keep the environment the same. Jumping 10-20 degrees made a MAJOR difference in my economy staying with the same grade.
You might want to go:
3 tanks of 87
1 of 93 for "cleanout"
6 of 93
1 of 87 for "cleanout"
3 of 87
Average the tanks of 87 then average those of 93 This should help account for increase in Temp and A/C. (unless you only drive 5000 miles/year.)

~SB

 

After 3200 miles, I am averaging 38 mpg.

 

using my chunky butt dyno, I can feel the difference between the power of the fit using gas from different stations.
my fit likes costco and samsclub 87 gas, I have never put in any higher, at $4.xx a gal it is hard to spend more.
I will give it a shot and fill up with 93 from costco at my next fill and will find out from corporate the ethanol content of 93 octane at costco.
as noted as above, it should NOT make any difference.

and seperate note, I did notice difference in power after stopping for and restarting the car, and resuming my trip on the hwy. it seems like some sensor heats up or something and the power/mpg diminishes.
Am I imaging things? should I double my meds....