Stop and go cools the engine /oil but heats up emission system and cylinder head which would add to carbon problems. I am sorry I misunderstood and agree with your mantra of try a few tanks and see for your self.

 

I filled up last week when I was just below half with Shell 93 and the OBC is already showing an increase in mpg and its been in the low 30's in the morning and low to mid 40's for a high. I think I'm sticking with premium from now on. I'm going back home to Detroit next weekend, so we'll see what my freeway mileage goes up to. I know its colder and the air is more dense, but we'll see.

Another one of my trip updates will be posted here next week after I get home. I got 39 going there and 41.5 mpg coming home last time, so we'll see what I get this time with full premium fuel, cruize on in the right lane going 70 mph, this is what I always do

 

That is what I seen in mpg and have noticed a better running car, Also mpg is more consistent.

I just got a bad tank of gas, premium will make the car run like it was suppose too with out knock, engineers put knock sensor on to prevent damage but at a cost of lower power and mileage. I expect to see a 10 percent decrease in mpg all winter because of the cold. I will explain this later in a new post when I have time.

 

You guys up north differ from the guys in the south in seasonal fuel usage but I have a hard time believing it is due to the density of colder air and think it has more to do with the use of snow tires, road conditions and accessories like heaters, air conditioners and lights in addition to longer and more warm up time for the engines.... I plan to drive a couple of hundred miles Monday and will be leaving early before sunup so I will top off my tank before leaving and on my return trip to see what kind of difference occurs, if any.... The early morning temperatures are in the 40s right now and afternoon in the mid 60s.

 

Typically up to right now is the best time for the best mpg. When its colder more fuel is needed to produce heat. More heat dissipates off the motor and more fuel is need to keep the motor running at temp. I notice more fuel is used during acceleration but is the same at cruise.Timing is the same so far for premium MBT.

Short trips in winter will kill mpg more than warming it up once to clean windows and driving your normal commute. Never had snow tires and wonder why its a big subject, except to protect stock rims. I never had any problems going through snow and slush in my Fit. I went down streets that would surprise most of the people on this site with no problems.

 

You can dyno an auto, you have to disable the traction control. I found my dyno results from 2 years ago and did very well. This is a dyno of GD3 Fit with vtec Jazz 1.4 & 1.5 i-DSI Power If you look at the stock hp and then compare it to the build up you would agree that running premium does benefit. I had a stock Ge3 Fit with a vtec, manual. Here are the numbers and when I get my scanner fixed I will scan it. 91.1 horsepower at 5800 rpm and 88.31 Torque at 4800 rpm all stock running BP premium at 6000 miles on car. Sorry wrong one http://asia.vtec.net/hardcore/JazzPower1/index.html

 

Colder air has a bigger impact than you'd think. My 38mpg & 1yr thread shows one winter's worth of driving on the stock tires. a little of it has to do with warming up the car but not too much as it doesn't take much to warm up the fit's engine. if you think about it, a Cold Air Intake is designed to grab colder air from the engine bay than a Warm Air intake so that the engine will have more oxygen to detonate. (CAI's in general produce more power because of the temp difference) With More oxygen, means more gas as the computer keeps the ratio of oxygen to fuel even. The same happens when the temperature drops but at a much more drastic rate. CAI's usually have a modest boost in power over comparable WAI.

My lifetime AVG right now is just over 38mpg and My last few tanks have been high 38s & lower/Mid 39s (our average temperature has been around 40 degrees when I'm driving.) When the AVG temp is in the 70's or 80's I'm up around 40 or 41+mpg. As we get into the winter I'm expecting to see 36 or 35 like last year with some really cold spells at or below 0F. The car is garaged in the winter so the starting temp when I leave in the morning usually doesn't get much lower than 32F but the drive is at times below 0F (usually in February).

If I were to guess, the 6-8mpg difference I see between summer & winter is probably 50% due to Temp and 50% due to other reasons such as different gas, Idle/warm-ups/clearing of snow.

~SB

 

When the air into the intake is denser the ECU is going to adjust A/F ratio no richer than it would when the air is warm and isn't as dense so the amount of throttle opening needed to accelerate and maintain speed will be less..... I can remember an older thread where a guy blocked off his grill and did get noticeably better fuel mileage which supports what you are saying. Already this year I am seeing better fuel mileage due to lower temperatures....I have been seeing higher speeds at the same throttle position on days when the temperatures are relatively low.... My car is far from stock right now but when it was stock I noticed the same thing... The higher wind speeds during the winter is going to have a negative effect even when blowing from the side.... The amount of fuel mileage loss when driving into a head wind will be slightly over compensated for on the return trip where it is to the rear of the car.... My last tank of fuel yielded only 31.7 MPG but I believe this tank is going to be better.. If not I will reconnect the throttle body heater and possibly install the stock heat range spark plugs.

 

Agreed, Colder air is denser so more fuel is needed to get it to the same fuel air mixture. Thats where the extra power comes from. In Stop and Go I get worse mpg but at highway speeds or continually moving it the same as in the summer but averages lower due to idling and higher engine loads. In the summer it would use not more than 5 gallons a hour at full throttle but in the cold weather Ive seen it go up to 7 gallons an hour. The car still runs in MBT timing so I am waiting for it to go full advance due to lower octane required. But so far its the same timing in 20 degree weather which leads me to believe I could go higher in octane than 93.

 

After a week of snow and cold temps my Honda Fit Sport is getting 28 mpg. The snow is now melted and the roads have sand all over them. I have Bridgestone Blizzaks maybe that did something.

 

Okay, I just got back a week ago from a road trip to Nebraska. For the trip, we used 89 octane for the price advantage over 93, since it was mostly going to be highway miles. At a speed range of 60-75, and an average of 65 MPH, we got 36-37 MPG over 1,100 miles, per ScanGauge. Response was good overall, although not quite as snappy as with 93.

I noticed that most places along the way, and in Nebraska, didn't have 93 octane fuel. 91 or 92 would usually be the highest. This seems odd given the low altitude.

Also, in Nebraska, I noticed there wasn't always such a large price difference with the various grades. In fact, on the return trip, I filled up with 89 octane, and noticed while driving out that 91 was cheaper! Put that in your gas tank and burn it!

EDIT: that station was in Lincoln, NE.

Also, as you might expect, there were more E85 stations in the Cornhusker state. Not as many as I would have expected, though. One in Grand Island actually had E10, E20, E30, and E85 to choose from.

We took it slower on the way back--about 55 to 65--and got 38-39 MPG as a result. The last tank was started in Tennessee, and I drove more nicely on the way home. I just finished, with 505.3 miles on the tank.

And yes, I just filled up with 93.

SECOND EDIT: I did fill up with a 1/3 blend of E85 once during the trip.

 

How are you able to run a 1/3 mix of E85 in our car, did you read somewhere that that's ok to do, just curious

Also, how in the heck were you able to drive less than 65 on a road trip, especially through Nebraska where its 75 mph in a good chunk of the state via I-80.

Even going through Tennessee I couldn't go that slow either but that has more to do with getting up and down those hills on I-75 if you go that way.

Your mileage is pretty damn good for this time of the year for sure, your doing something right

 

I have read conflicting things regarding E85, but nothing conclusive; I'm running partial mixes of E85 as an experiment so others will have solid reports as far as whether it's safe to run in a Fit. So far, I've run mixes up to E40. The only problem I've had so far is a Check Engine light, which gave a P0171 code (Long Term Fuel Trim Lean). As I understand it, the reason for the code is all that extra oxygen from the ethanol; it's not actually running lean. I don't know yet whether our fuel injectors could cope with straight E85, since they'd have to flow 30% more fuel.

Road trip speed: I had 2 other drivers sharing the load on the way there, and 1 on the way back, so it wasn't that bad. As for me, personally, I find it pretty stressful to drive very fast, so I actually have better endurance if I go around 55-65.

And yes, those Tennessee hills were pretty bad, especially with a full load in the back.

I attribute my good mileage to good driving habits, driving a manual, my modifications to the car, and higher tire pressures (44 front, 48 rear).

 

I found some more info http://www.state.mn.us/mn/externalDo..._E20Report.pdf Its a good read and goes into the problems. I will continue to use 93 octane gasoline.

This is another reason to use premium gas http://www.crcao.com/reports/recents...9%202%2004.pdf As the gas sits it the tank it loses the light ends reducing octane and raising the need for higher octane. Ethanol seems to speed this up too. All this on top of colder weather and longer warms ups reduce the mpg of any car.

 

55 on the freeway isn't for everyone but if your comfortable with it and don't care about the looks you get, good for you! It does remind me of that one commercial for Castrol, I think, where the guy has an anchor dragging behind him on the freeway

Now your air pressure is ok if the tires can handle it but man it must be a bumpy ride for sure. I run 36-37 psi all the way around during the winter so I don't have to worry about losing psi with the cold temps here in Chicago. The only thing I'd worry about additionally with your psi settings is the middle of the tires wearing out because of over inflation.

The use of E85 is a little too risky for me to try, but what are those other numbers and letters you've put up for the E85, I'm not familiar with that

 

Ignoring whether or not the alcohol will eat various rubber seals in our pumps, regulators or the inside of fuel lines, or if we have enough pump and injector to keep up with the fuelling demands of E85, even a 1/3 mix... But outside of all that I do not see any compelling reason that E85 would be bad for our cars. I intend to run it in the Fit when I boost it. But I will be using a pump and injectors certified for ethanol, PTFE braided lines, and an Aeromotive regulator.

From what S&D is describing, the E85, even 1/3 tank, puts the fuelling requirement outside the ability of the Fuel Trims to adjust for. This could lead to a seriously dangerous lean condition under load.

This would make me very hesitant to do this on a stock ECU. But I will be running the AEM by then so we shall see what the actual figures are for various blends or E85.

If I can find a way to get a second fuel rail installed, I would prefer to go E98. Nothing quite like unleaded, oxygenized ~114oct pump fuel!

 

I'm very happy with my switch to BP Ultimate and I know the E85 is higher octane, so you boosted guys can really take advantage of that for sure. I know a guy back home that trailered his EVO VIII here to AMS and had the car tuned for E85....it puts down 375 whp on their dyno, amazing what an extra .4 liter and a hairdryer can do to an engine

Hell, just want another 30 hp/30 ft/lbs of torque and I'd be able to call it a day for this car

We'll see how my mileage does this week on the next fill up. Thanks for all the info supplied here, I know I find it interesting and its very informative too!

 

Here more info on ethanol blends in cars http://www.ethanol.org/pdf/contentmg...inal_12507.pdf not what I was looking for but will keep looking.

 

Thanks for the links, SilverBullet.

@Klasse Act: the term E85 means 85% ethanol. The rest is gasoline. They reduce it to about 70% during winter months. I use the term E40 to refer to a blend which I calculate to be 40% ethanol. If you make such a calculation, remember that the "normal" gasoline is probably 10% ethanol, or E10.

 

Heres more info from the epa http://www.epa.gov/otaq/presentation...-isaf-no55.pdf, http://www.afdc.energy.gov/afdc/etha..._research.html