Gas Mileage

[cwa107]

Originally Posted by N_Jay

That was not what was being discussed.

"Miles per tank" is about the worst way to track milage.

OK, to me, mileage per tank is the amount of mileage on the tank divided by the number of gallons I add to it.

I do agree that a single tank is not a significant data sampling, but you can get a pretty good feel for the actual MPG attained over the course of several tanks.

[moda_way]

Originally Posted by N_Jay

Sorry,. I should have been more clear.

I was addressing this part;
"Tires were inflated to 36psi and probably should've done 38-40psi, but given the load and heat, I didn't want to go there."

The greater the "cold" inflation, the less the temperature rise with use.

The greater the load, the greater the temperature rise with use.

Ac has nothing to do with tire temps or rise.

Pressure build due to temp rise from use is already taken into account when calculating proper and maximum tire pressures.

Ah, that makes more sense. I know the listed PSI on the door is 36psi, which is what I run at cold, hence my running PSI is usually close to 38-40psi, so I didn't want to inflate to 40psi cold and have it at 43psi running (i.e. no real reason to do so).

I also agree, A/C has nothing to do with tire temps. My point was to link to load on the motor.

[N_Jay]

Originally Posted by cwa107

OK, to me, mileage per tank is the amount of mileage on the tank divided by the number of gallons I add to it.

I do agree that a single tank is not a significant data sampling, but you can get a pretty good feel for the actual MPG attained over the course of several tanks.

How to get better gas mileage?

[RSQ Pilot]

Originally Posted by moda_way

Ah, that makes more sense. I know the listed PSI on the door is 36psi, which is what I run at cold, hence my running PSI is usually close to 38-40psi, so I didn't want to inflate to 40psi cold and have it at 43psi running (i.e. no real reason to do so).

I also agree, A/C has nothing to do with tire temps. My point was to link to load on the motor.

Check your tire psi on the door jamb.....mine says 32 psi for the 2009 Touring

[hondapilotjim]

Originally Posted by N_Jay

First we don't know how "full" each persons "Full" is.

Even if everyone always stopped filling at the "first click" it is not the same for every car or every pump or every time.

Even if we assume it is the same for every car, pump, and time; we don't know how empty everyone considers their "Empty".
Is it when they start feeling it is;
"Too Low",
When the light comes on,
When the gauge in on "E".
Below "E"?

Even if everyone agreed that it is the same point on the gauge;
We don't know how far each person drove after getting to that point before getting gas.

Plus when looking at "Miles per talk" people focus on the "Best" or what they "Feel is the average", making any valid comparisons of something that is as variable as fuel consumption completely impossible.

hey thanks jay!

[hkellogg]

I've gotten 15.5mpg since I bought my 07 last month

[TriKKy]

3,836 miles, 219.72 gallons = average of 17.46MPG

Maximum: 19.63
Minimum 15.64
Total Costs: 570.15
Total Fillups: 11
Total Days: 97
Cost per Mile: 0.15
Cost Per Gallon: 2.59
Cost per Day 5.88
Cost per Fill up 51.83
Gallons per fill up 19.97
Miles per fill up 348.73
Miles per day 39.55
Miles per $ 6.73

I'm doing a longer commute to work now and so far has been getting better mileage (19-20 range). I don't exactly drive slow either but do sit through about 20 minutes of bumper to bumper traffic each way every day.

---------------

Regarding the high PSI numbers.....yes you get better mileage, less rolling resistance. You also get uneven wear on your tires (middles wear faster than edges). You also get longer stopping distances.

---------------

Here is as good a place as any to ask: I pretty much always add 2 gallons of gas after the first pop while filling up and have NEVER overfilled. This seems pretty extreme. My Accord normally takes 1 extra gallon. Anyone else notice this?

[N_Jay]

Originally Posted by TriKKy

---------------

Regarding the high PSI numbers.....yes you get better mileage, less rolling resistance. You also get uneven wear on your tires (middles wear faster than edges). You also get longer stopping distances.

---------------

Maybe maybe not.

OVER-inflation will wear the centers unevenly, but with radial tires I doubt you will get into this situation.

Running high but not extreme (Between the door sticker and a few PSI under the sidewall rating) will usually give you better tire life overall.

EDIT: Found this
http://www.nhtsa.gov/cars/rules/ruli...ure/LTPW3.html
Seems stopping distance IMPROVES with higher pressure.

I am not sure where the stopping distance information comes from. A higher pressure tire will hydroplane less, but a too hard tire will loose traction on rough surfaces. There are lots of factors in both directions.

In general every aspect of a tire gets better with higher pressure except ride comfort. (as long as it is in the safe range; above the door sticker and below the sidewall rating)

[offroader]

18mpg average - city driving with some construction work, bumper to bumper and some normal traffic conditions.

[TriKKy]

Originally Posted by N_Jay

Maybe maybe not.

OVER-inflation will wear the centers unevenly, but with radial tires I doubt you will get into this situation.

Running high but not extreme (Between the door sticker and a few PSI under the sidewall rating) will usually give you better tire life overall.

EDIT: Found this
TIRE PRESSURE SURVEY AND TEST RESULTS
Seems stopping distance IMPROVES with higher pressure.

I am not sure where the stopping distance information comes from. A higher pressure tire will hydroplane less, but a too hard tire will loose traction on rough surfaces. There are lots of factors in both directions.

In general every aspect of a tire gets better with higher pressure except ride comfort. (as long as it is in the safe range; above the door sticker and below the sidewall rating)

I very strongly disagree that every aspect of a tire gets better with higher pressure except ride comfort. Comfort, handling and by extension safety, predicatability, resistance to blowouts (not that under-inflation is any better) all are worse.

Everywhere I read indicates that over-inflation does not lead to better tire life overall. If it were the case that higher inflation is better then I would argue that vehicle and tire manufacturers would recommend it, especially given the fact that you do get better mileage from over-inflation. Car manufacturers would do just about anything to get more mileage out of their vehicles, I site the fact that they are using 5W-20 oil. If they can get better life out of the tires and better mileage why would they stick to their original recommendations if they only had to sacrifice a little ride comfort...heaven knows they aren't against giving up some ride comfort given the use of run-flats?

I see the numbers in the report, and I would be no means argue with data, it is what it is. The problem is that this is ideal situation data and I am not sure if the differences are significant so in ideal situations, you appear 100% correct and I was wrong in saying that distances are longer.

The thing to remember however is that few roads are ideal. Over inflation by even 6psi will increase the risk of blowout as the tire has less give when shocked. Additionally, the harder/less forgiving tire will "bounce" more on uneven roads. So you are sacrificing ride comfort and secure handling. But remember, that those bounces can happen while stopping as well. If your tire isn't on the ground, it would stop as fast.

Also, and again going back to the data, I still feel like it doesn't make sense even though it is what it is. I would like to research more. More inflation = less rolling resistance due to less tire actually touching the road surface. I would imagine that less touching would mean less friction generated by the tire meaning longer stopping distances. Perhaps the test results are a function of ABS and trying to prevent tires from fulling locking up.

I am certainly no expert and I just have a different opinion here based on what I've read and seen. If I'm wrong I'm wrong and it wouldn't be the first or last time in my life.

[maxummus]

I went on a 3 day trip and I rented a 6x12 cargo trailer and had about 1500lbs. of weight I was hauling with the 4x4 pilot and I got around 12.5 MPG on the Pilot. 80% highway driving and 20% city

[N_Jay]

Originally Posted by TriKKy

I very strongly disagree that every aspect of a tire gets better with higher pressure except ride comfort.

You have the right to your opinion.
You also have the right to be wrong.

Originally Posted by TriKKy

Comfort, handling and by extension safety, predictability, resistance to blowouts (not that under-inflation is any better) all are worse.

I don't know where you list comes from, But;
Handling, predictability, and resistance to blowouts ALL get better with greater pressure.

What people seem to get hung up on are the problems with OVER-inflation (Above the sidewall rating). I am not talking about taking a tire to these levels.

Originally Posted by TriKKy

Everywhere I read indicates that over-inflation does not lead to better tire life overall. If it were the case that higher inflation is better then I would argue that vehicle and tire manufacturers would recommend it, especially given the fact that you do get better mileage from over-inflation. Car manufacturers would do just about anything to get more mileage out of their vehicles, I site the fact that they are using 5W-20 oil. If they can get better life out of the tires and better mileage why would they stick to their original recommendations if they only had to sacrifice a little ride comfort...heaven knows they aren't against giving up some ride comfort given the use of run-flats?

You are quick to make assumptions.
First, ride comfort IS very often a decision feature when buying a car. Look at the number of people who complained when dealers did not adjust the tires down from the shipping pressure of 40 PSI during the Pre-Delivery Inspection.

As for tire life, I can only go by what I know about tires and personal experience. Tire life and tire wear are directly related to the amount of flexing of the tread during use. A higher pressure reduces the amount of flexing and hence lowers internal temperatures and tread squirm. Even when rolling perfectly strait, the tread has to squirm or scrub against the pavement as the tire carcass deforms due to the weight of the vehicle. This is a significant component to tire wear.
Not to mention of the internal wear from flexing the sidewalls. Have you noticed how many "blown-out" tire you see these days with the sidewall destroyed and the tread nearly intact.
These are NOT "Blow-outs"! These are tires that were run for miles at highway speed UNDER-INFLATED. Today's radials ride so well that most drivers never notice a flat tire until it destroys itself.

As for Run-Flats, the three cars I have driven with them did not seem to suffer from ride problems. What is your experience?

My experience is that I run my '03 pilot between 36 and 40 PSI. (Usually set at 38 for normal driving and 40 for towing.) I don't run above 40 because ride comfort starts to seriously deteriorate.

I got 65,000 miles from my (crappy, as people like to call them) GY Integraties and 100,000 miles from my Michelin Cross Terrains.

Originally Posted by TriKKy

I see the numbers in the report, and I would be no means argue with data, it is what it is. The problem is that this is ideal situation data and I am not sure if the differences are significant so in ideal situations, you appear 100% correct and I was wrong in saying that distances are longer.

I think what was more interesting is that there really is very little difference.
Other than hydroplaning, where higher pressure is ALWAYS better, and some mention of tire bounce, where lower pressure is assumed to be better, I have never heard people use stopping distance as a general issue with tire pressure.

Originally Posted by TriKKy

The thing to remember however is that few roads are ideal. Over inflation by even 6psi will increase the risk of blowout as the tire has less give when shocked.

Where does this number come from?
6PSI over what? (Again, I am NOT talking about going over the sidewall rating)
I have never seen s tire "Blow-out" due to an impact. The usual failure mode is a sidewall cut due to pinching the sidewall between the tread and the rim, MORE LIKELY at lower pressures, and knocking the bead off the rim (only happens at low pressure (Typically off-road when you air-down your tires).

Originally Posted by TriKKy

Additionally, the harder/less forgiving tire will "bounce" more on uneven roads. So you are sacrificing ride comfort and secure handling. But remember, that those bounces can happen while stopping as well. If your tire isn't on the ground, it would stop as fast.

Here is where we agree. I am faily confident that unless you really like riding on hard tires you woudl not get to this range if you use ride comfort as your upper limit.

Originally Posted by TriKKy

Also, and again going back to the data, I still feel like it doesn't make sense even though it is what it is. I would like to research more. More inflation = less rolling resistance due to less tire actually touching the road surface. I would imagine that less touching would mean less friction generated by the tire meaning longer stopping distances. Perhaps the test results are a function of ABS and trying to prevent tires from fulling locking up.

Most rolling resistance is not related to the friction against the road.
It is due to energy lost heating the tires due to flexing the sidewalls and tread and scrubbing of the tread during that flexing.

While contact area goes down contact force goes up. IF you remember your middle school science experiment on friction, you will return to the same sense of amazement when you realize that the total friction stays the same.

[thecaptain]

just back off a 140 mile trip through Long Island, the Bronx and up to Monticello.

The car's trip computer had me at 22.4 MPG, mostly highway and using the car's cruise control while driving barefoot off cruise control at times. Most of the trip was over 70 MPH.

I use the car's trip computer "B" setting and that has given us 18.5 MPG over the last 10,000 miles under usual 50/50 mixed driving.

I also used a mileage calculator on our Garmin. It tagged us at 20 MGP over the course of the trip.

New note re: getting the best mileage.
This is what I feel about getting better gas mileage:

I used to NEVER use cruise control as I felt that my foot, a feel for the engine and a visual check on RPMs gave me a better idea of how to push the car along.

However, since a lot of this driving was long inclines as well as long downward valleys, I felt I should let the cruise control work the car through the hills and see if it gave better MPG. And it performed MUCH better than I did.

I was actively moving faster and slower using the cruise control dials on the wheel but very rarely did I touch the pedal. When I did, I always go barefoot barefoot, again,to get a better feel of whats going on.

I thought about this forum over the drive and had one question....

On the long hills going downward, I sometimes let it coast down by putting it in neutral. Honestly, I only did it a few times to see its effect on econ but wanted to know if this is damaging to the transmission?

[maxummus]

Originally Posted by thecaptain

just back off a 140 mile trip through Long Island, the Bronx and up to Monticello.

The car's trip computer had me at 22.4 MPG, mostly highway and using the car's cruise control while driving barefoot off cruise control at times. Most of the trip was over 70 MPH.

I use the car's trip computer "B" setting and that has given us 18.5 MPG over the last 10,000 miles under usual 50/50 mixed driving.

I also used a mileage calculator on our Garmin. It tagged us at 20 MGP over the course of the trip.

New note re: getting the best mileage.
This is what I feel about getting better gas mileage:

I used to NEVER use cruise control as I felt that my foot, a feel for the engine and a visual check on RPMs gave me a better idea of how to push the car along.

However, since a lot of this driving was long inclines as well as long downward valleys, I felt I should let the cruise control work the car through the hills and see if it gave better MPG. And it performed MUCH better than I did.

I was actively moving faster and slower using the cruise control dials on the wheel but very rarely did I touch the pedal. When I did, I always go barefoot barefoot, again,to get a better feel of whats going on.

I thought about this forum over the drive and had one question....

On the long hills going downward, I sometimes let it coast down by putting it in neutral. Honestly, I only did it a few times to see its effect on econ but wanted to know if this is damaging to the transmission?

I think its fine putting it in neutral when coasting. I use to drive a manual and I use neutral all the time when stopping and coasting.

[N_Jay]

Originally Posted by thecaptain

. . .

I thought about this forum over the drive and had one question....

On the long hills going downward, I sometimes let it coast down by putting it in neutral. Honestly, I only did it a few times to see its effect on econ but wanted to know if this is damaging to the transmission?

I doubt it would hurt the trans.

(and as I am sure you know, it is illegal in most states)