haha i've been reading that in many of the eco threads I do believe that but it seems wheel pressure is a very important factor to get a much better mpg. mine are factory recommended at 32psi and with conservative driving I get max of 35.8 so far. Must test the higher psi sometime

 

I also forgot to mention before, that I have been running Royal Purple 0W30 since about 1500 miles. That, I can attest to, really does make a difference. And Royal Purple "Purple Ice" coolant additive. And I mounted my IAT in the new SRI today using a 5/8" hole saw bit and the factory rubber grommet, so we will now see if that helps/hurts.

 

It's interesting seein how many people actually fill their tires to the maximum pressure (according to the tire mfr.) trying to raise mileage. Yes, it works great... but you run a risk. Tires and the air inside them heat up thus increasing air pressure. So even though when you checked it in the driveway it was 45 psi, on the interstate it's closer to 55 . Not only is overinflation a hazard... it's also EXPENSIVE because you'll wear out the middle patch of your tires WAY faster. Extreme tire wear + High pressure = BLOWOUT. Heck. you might loose money, because a replacement set of tires may be well over the amount you saved in gas . I'll keep mine at the manufacturers specs

...Just saying

 

That's why you do what I did and use nitrogen.

Completely non-reactive to temp. If you put 45psi in it, it's 45psi from now on whether it's -25 degrees or 125 degrees.

 

No.

I've covered this in a previous post on nitrogen-filled tires. Here we go

But here's the gist of it...
The pressure of a gas changes based on temperature... Charles' Law

Don't fall for this bologna!!! Perhaps Nitrogen gas in tires has other benefits, but ALL GASES change in volume (therefore, pressure if confined to a fixed-sized space) based on temperature - so no pressure change due to temperature is NOT one of the benefits.

Sorry - but if that's what the service station told you who filled your tires - you were lied to.

 

I worded it wrong.

Ambient air contains moisture, which nitrogen does not. If moisture is there, it contributes to a greater change in pressure with greater changes in temperature. A liquid form of water occupies very little volume and contributes only a negligible pressure to the tire. But at higher temps, water becomes a gas; water evaporates inside the tire as temperature rises. This greatly effects pressure.

Also with ambient air, which contains about 20.9% oxygen, the oxygen permeates through the rubber of the tire, so some leaks out. With nitrogen, pressure changes due to oxygen loss are greatly reduced. The nitrogen molecules are quite a bit bigger than oxygen.

Nitrogen is dry; it has no moisture to contribute extra pressure changes with temperature. And nitrogen permeates out much slower than oxygen, so pressure changes due to that leakage are almost eliminated, compared with ambient air.

So with less oxygen and less moisture, the remaining nitrogen is less affected by leakage and by temp changes than a tire with oxygen and higher humidity.

 

so i guess its safe to assume that getting this type of mileage requires something other than frugal driving.


the best tank i ever got was 39.6 mpg and that was averaging about 60-65 mph on the free way for very long stretches all at cruise, with no inclines.

 

I'm stating to get a tad concerned. I'm on my 4th FULL tank with around 1400miles on my Fit.
On my 40.6mpg last tank, I saw 120miles at 3/4 tank mark. I'm at 165 now just coming on 3/4 tank.

I 1 sec drafted 1/2 of a double wide on the way home today. Was looking at 50mpg on my scanner most of the way at 60mph.

 

I was thinking Boyle's law had more to do with a tire and pressure.
Boyle's law - Wikipedia, the free encyclopedia

 

Not bad at all!

 

When I have achieved 40mpg(which is the last 2 tanks) I have driven at the speed limit or only 5mph over(60mph). Tires have been at 35psi and 40psi. I use Cruise control whenever possible and coast with tranny in neutral when ever possible. I shift from 2.5-3K and I have done this by starting off in 1st or 2nd gear. Another thing people have not really mentioned is the outside temperature. When it is cold or hot no one gets great mpg. Also, I have accelerated by slowly, changing gears in about 3 seconds, when shifting in the 2.5k range. I also, drive 60 miles one way each day which entails about 3/4 highway and the other 1/4 is city. The only mod I have is a short shifter. Oh, I do use Mobil 1 synthetic oil. I have 22k on the car now.

 

I think Boyle's law just goes a few steps further than Charles' law. I'm not certain... I havent had Chemistry since I was a sophomore in college.

I wish I actually used all those mathematics and science courses for something besides just general knowledge....

 

I am still wondering how everyone is getting such great gas mileage myself. When i first got my fit i got around 33mpg and the highest was 35mpg. Now im several tanks in with almost 9k miles on my car and barely getting 30mpg. I dont gas hard, break hard and i shift at 2.5-3k rpm. my tires are at manufacturers recommendation and im not even getting any where near 35mpg. i also do alot of mix driving and fill up when the light comes on. when i do fill up i dont top off (OVERFILL). so it is mind boggling and astounding for me to hear people getting 40+mpg when im trying to reach 35mpg. I also have the 1.5L if that makes any difference because i know there is also the 1.3L for other countries not US.

Also how are you guys calculating to get your MPG. for me i reset my trip meter at eat full tank then on me next full tank i devide the total miles i accumulated by the amount of gas i put in.

ie: 268.5 miles from the full tank and i used about 8.7 gallons of gas to fill up.
268.5 / 8.7 = 30.76 MPG
This is somthing that i would actually get. i know this has been talked about in many other threads but please humor me.

 

just wondering... what do u have your climate control on? defrosting/feet? i get about 35 and up. i commute 50 miles on the hwy. 580. (with the rolling hills). i tend to hypermill behind a rig up hill and keep it at 60. every now and then i just punch it. i also turn on my AC from time to time. for me.. i fill it up til it "click" and then on the next's trip i do the same. mileage/gallons filled = MPG.

 

I hate using defrost and AC but i do have the circulation from outside air comming in. i also have the hood deflector jdm window visor and when i got me last station chamber intake and megan axle back it brought my mpg up to a consistent 29-30mpg. before it those installation it was roughly carying btwn 26-30mpg.

 

I can list at least 5 things that will help if you want to try

 

sure im open to ideas that will help me out.

 

Keep it under 65mph, over 65mph and you'll get low 30s on mpg

 

hate to burst your bubble there doc, but my fit gets over 40mpg going 70-75mph and gets under 40mpg going 60-65mph. stock, auto, sport.

 

OK Here ya go, but I'd like feed back when you do it all with your expected success.

1. Increase tire pressure to at least 10psi UNDER the max pressure listed on the tire sidewall and measure it a few times hot to make sure you do not exceed the max pressure (when hot). If it's a Sport just go to 45psi and check it a few time HOT.
2. Drive like you have a RAW EGG between your foot and the gas peddle.
3. Shift no latter than 3krpm's
4. When driving 50mph or greater, try and find a large box truck and draft it no less than 1 sec back. Of course when doing this make sure you pay attention to the distance and his stop light. I find it best to hold back on speed till one passes than fall in behind him.
5. Go no faster than 65mph, except when drafting and than it's not worth it if they exceed 70mph.
6. Do not use the A/C or defroster unless you have to. Crack the windows and use a towel to clean the window of condensation.
7. Look way down the road and when you can coast into a stop and when close enough that brakes are needed, use the 5th gear to slow the car. The idea is use the brakes as little as you can.
8. If you pull into a major intersection, as it just goes red, stop the engine and get ready to start as your side goes green.
9. Remove all personal items that weigh from the car that are not needed.
10. Use the Honda recommended weight oil and keep the Air filter clean.

I had responded when this thread came up on the site to the originator Black01 with some help and than deleted my contribution when I detected an attitude about the recommendations. Now I kind of laugh at this thread as most of this is in the Eco area of this Form, but many Fit owners still feel their Fit is defective and they can't believe 40 is possible.