Anyone overcoming gas prices by hypermiling?

[RunningBum]

Quote:

Originally Posted by Notmuchlonger No, because you are in the air the semi already cleared. (which is a super simple explanation) Thats the problem sudden stops.

This was a Car Talk question this week! They agreed with you.

[Notmuchlonger]

Quote:

Originally Posted by RunningBum This was a Car Talk question this week! They agreed with you.

Im qualified. I watch Nascar

[HFWR]

But you have to be going 180mph to draft off a car.

[mb]

Quote:

Originally Posted by Bestwifeever Re drafting behind a semi on the highway--wouldn't that hurt the semi's MPG to be pulling you along? I could see some sudden stops on the truckdriver's part to deal with that problem....

No the guy in front actuals benefits also although not nearly as much as the guy in the back. I think that it reduces wake turbulence.

At least that is the way that it works for bicycles. I assume that it works the same for car.

MB

[Zathras]

Quote:

Tailgating can get you dead fast. You need to get within 10 feet of the truck in front of you to get a mileage boost.

The tests I saw and from what I have seen there is a noticable benefit to following a semi as far as 20 car lengths. True, the most benefit is at 10 feet, but I agree with you on that, it would be crazy.

[cute fuzzy bunny]

Seems theres some misinformation on octane being thrown around.

Higher octane fuel has less total energy than lower octane fuel. It is not a "better" product, with a set of engine parameters it will produce less HP and lower gas mileage.

What it IS good at is lowering the tendency to detonate prematurely in an engine with higher compression ratios and/or higher heat in the combustion cylinder. That stability is gained through a loss of total energy during combustion.

Some engines will adjust the engine timing to reduce detonation if its detected, so you can use lower octane fuels. The retarded engine timing also reduces mileage and any detonation or knock (which may be undetectable to the ear) can damage pistons and valves.

Its highly advised that you use the fuel octane the manufacturer recommends. This is also a really bad place to try and save some money.

I also see the mileage increasers are recommending a reduced viscosity oil. Unless the engine manufacturer recommends it, I would not use less than a 30 weight oil especially if you operate in a climate over 80 degrees. Engine jobs are a lot more expensive than gas.

[ERD50]

Quote:

Originally Posted by cute fuzzy bunny Higher octane fuel has less total energy than lower octane fuel. It is not a "better" product,..

Agreed.

Quote:

with a set of engine parameters it will produce less HP and lower gas mileage.

Sort of. If those 'engine parameters' dictate high grade only, you need to use high grade. If it is designed for low grade, then yes, high grade will give lower mpg.

Quote:

What it [high grade fuel] IS good at is lowering the tendency to detonate prematurely in an engine with higher compression ratios and/or higher heat in the combustion cylinder. That stability is gained through a loss of total energy during combustion. Some engines will adjust the engine timing to reduce detonation if its detected, so you can use lower octane fuels. The retarded engine timing also reduces mileage and any detonation or knock (which may be undetectable to the ear) can damage pistons and valves.

Exactly - and this is why some say that in a car designed to take a range of fuels (many of today's vehicles), high grade may improve mpg - because it can adjust the timing for better efficiency.

My guess is that if you drive conservatively anyhow, you will rarely hit those times when the engine needs to retard the timing to avoid knock (normally only under hard acceleration). So I also guess that high grade won't help conservative drivers get better mpg, but it may be possible.

Quote:

Its highly advised that you use the fuel octane the manufacturer recommends. This is also a really bad place to try and save some money.

Yes, don't try a lower grade unless your manual says it is OK, like I said.

Quote:

Seems theres some misinformation on octane being thrown around.

Where was the misinformation on octane? I missed it.

-ERD50

[Texas Proud]

[quote=cute fuzzy bunny;653748]
Some engines will adjust the engine timing to reduce detonation if its detected, so you can use lower octane fuels. The retarded engine timing also reduces mileage and any detonation or knock (which may be undetectable to the ear) can damage pistons and valves.
quote]

Yes... I have a car that 'requires' 92 octane... but it says you can get by with 87... but reading up on the results, it retards the timing and whatever else it does and the HP is lower and also the MPGs are lower...

And my thought.... if you paid a bundle for a car that NEEDS high octane then why cheap out and buy low octane fuel Decided upfront what grade gas you want and buy a car that uses it...

[ziggy29]

It's not worth an extra 5 MPG to significantly increase my chances of plowing into the back of an 18-wheeler. I don't care how much gas costs.

[free4now]

Overpressure is probably safer than underpressure. I don't have any statistical evidence, but it seems to me I've never suffered overpressure problems. Most of my tire failures in the past have happenned when I hadn't checked the tire pressure in a long time; I'm guessing the tire had too little pressure so the rim scissored it going over a bump.

A larger contact patch will also increase the amount of road debris (e.g. nails) collected by the tire. Also a large floppy contact patch has a tendency to work debris into the tires, whereas a small taut contact patch has a tendency to push debris away.

The right amount of pressure is the amount that causes even tire wear... the environmental and monetary costs of replacing tires early are not worth any gas savings that might accrue from hyperinflation. I measure my tread depth (center and sides) every time I get an oil change with a $2 gauge, so I know that my 42psi gives more even wear than the 33psi manufacturer recommended pressure.

[ziggy29]

Quote:

Originally Posted by free4now The right amount of pressure is the amount that causes even tire wear... the environmental and monetary costs of replacing tires early are not worth any gas savings that might accrue from hyperinflation. I measure my tread depth (center and sides) every time I get an oil change with a $2 gauge, so I know that my 42psi gives more even wear than the 33psi manufacturer recommended pressure.

The manufacturer of the vehicle may be making recommendations based on the smoothest ride, not necessarily what's necessary for the rest of the vehicle to perform as it should.

[cute fuzzy bunny]

Believe it or not, that was a deciding criteria for a car I bought. I had it down to two that I liked about equally and couldnt make up my mind. One took regular, one took premium.

So I bought the one that took regular.

[TromboneAl]

Quote:

Originally Posted by Bestwifeever Re drafting behind a semi on the highway--wouldn't that hurt the semi's MPG to be pulling you along? I could see some sudden stops on the truckdriver's part to deal with that problem.... No, because you are in the air the semi already cleared. (which is a super simple explanation)

The only important thing is whether the (beer drinking, speed-taking, hairy-knuckled, pot-bellied, shaver-challenged) trucker thinks you are hurting his gas mileage.

[haha]

Hypermiling is crazy. Millionaires trdading a marginally increased gas mileage for an increased risk of death is not smart.

Ha

[Notmuchlonger]

Go Dale Go!

[haha]

Was he drafting when he bought it?

ha

[Notmuchlonger]

Dale Jarett? Nah just a UPS commercial. Hes retiring this year. He hasnt bought it yet. The whole drafting thing reminds me of Nascar something fierce...

[cute fuzzy bunny]

If anything, I'd think they were already pushing it a bit.

I've been a little leery of my Pilots call for 5w20 oil...I think its getting 5w30 before the 110 degree heat sets in...

[LOL!]

I'm surprised this thread is concentrated on drafting and tire pressure. The two things that I do to increase mileage is coast, don't use my brakes, and turn off the engine at stop lights that I know are gonna take awhile. I get more than 20 mpg in city driving in my SUV. That may not be much to you Prius folks, but it's more than the EPA-rating for this vehicle.

Perhaps the most irritating to other drivers is coasting. I live about 3 miles and 6 stop lights from my job. I know all the light timings, so I will coast up to a half mile towards a red light or a light that is going to be red. Of course, the woman behind me in her Navigator or Sequoia or Escalade gets irritated and zooms around me towards the light at 10 mph over the speed limit only to slam on her brakes as the light changes to red. I coast up just as the light turns green and pass her while she is still stopped. It all repeats at the next light.

[cute fuzzy bunny]

Side note: checked the tire pressure on my trailer tires for the first time in a few months.

Five in one and eleven in the other. Looked at the sidewall and they're rated for 90.

I turned my head a little when the compressor had them north of 60, just in case...