Any hypermilers? And busting myths.

[kanonfodr]

2. If I take my car out of gear (i.e., into neutral) going downhill, the rpm drops significantly. Are there any damaging effects of doing this? When I remember, I also put it in neutral at stoplights, and at long lights / traffic, turn the car off.

It depends on your transmission, re: downhill. However, coasting downhill is dangerous and in some states illegal. As far as the whole neutral at a stoplight thing I am doubtful since your engine is getting damn near the same amount of fuel at idle either way. The only reason I put my Jeep in neutral at stoplights is because my left leg gets tired of holding the clutch.

3. What kind of tire pressures do you recommend? I've heard that I should over-inflate my tires (more than design point, but less than burst pressure rating). My car specifies 31psi/tire, I've had decent success with 36 psi/tire. Any thoughts?

Never exceed the manufacturer's specification!! That being said, whatever criterium you are trying to meet (gas mileage, even wear, skidpad grip, etc) can only be measured by trial and error. Personally I would rather lose a little bit on gas mileage and enjoy the increased safety and tire life of having them filled for optimum wear. Also keep in mind that if you are typically making longer drives (over 5 miles) you need to account for gas expansion inside the tire as it warms up, which will increase tire pressure at operating temperature.

No, you've got it all wrong. This is ALL ABOUT aerodynamics, and the power/ energy required to maintain a given speed. Acceleration is not a factor here.
Every time you double your speed, say, from 50 to 100mph, the power required to maintain that speed quadruples.

In relationship to wind resistance yes, but if the object is slippery enough in the wind it will not need as much power at x speed to maintain that velocity compared to another object with a higher drag coefficient. Also, engines have an optimum powerband where the engine itself is working most efficiently and since the 'Vette is made to go much faster than 50mph (or even 90) it's not working as efficiently at 55mph as it is at 90mph. My Jeep on the other hand is MUCH happier at 55mph than it is at 90 (and I'm much happier at 55mph as well).

2. It shouldn't damage transmission. Be aware of one thing those it's not always best to coast in neutral. Many newer cars kill the injectors when the vehicle is a. In gear b. no foot on accelerator c. Roma over a set point (1000 Rpms in my jetta). So basically the engine down shifts the cars inertia keeps the motor turning but there is no fuel being used. Sometimes you can coast in neutral if your coming to a stop and it's far. If you realize your stopping sooner than expected or going down a hill instead of using your breaks in neutral keep it in drive and let the engine break it.

Wow...ever studied an internal combustion engine? So much mis-information. Best bet, leave the vehicle in gear and quit whining about your gas mileage.

3. Tire inflation can actually make a large difference. The common misconception about tire pressure is lower pressure makes the tire wider. It does only slightly, I only know this because I'm also an offroad enthusiast it greatly increases the lateral contact or length of the tire contact patch front to back. Never exceed the tire pressure on the tire. I usually inflate to 5psi below max.

True...enough. But optimum tire pressure for whatever criterium you hope to achieve is best found empirically.

5. I believe in the list above it says and I sometimes do switch on a/c till the car gets cooler and then turn it off manually. Or don't use it at all and just leave the blower on with the a/c off or economy mode on. The way I understand it. The a/c is either on or off there's no I between. So if you think keeping the thermostat just a little cool helps it doesn't. A/c is fully 100% on and there is a blend door that blends the air to the temperature you want.

But your compressor (the part that does create parasitic loss on the engine) isn't always on, it has a clutch that engages and disengages as needed. How often it does so? Depends on your AC system.

Partly right. shifting into neutral WILL cause you to need to replace transmission linkages, etc sooner on an automatic, as they are not designed to be manually switched. That repair, depending on the vehicle, is FAR more than what you will save in fuel over the life of your car.

TL;DR: DON'T MANUALLY SHIFT AN AUTOMATIC!

Pretty true. Especially on the cost part.

Hunter Thompson suggested around 75 psi.

Hunter WHO?? Google turns up nothing related to tires, and 75 is racing bicycle territory. I've never seen an automobile that required 75 psi in it's tires. NOBODY FOLLOW THIS ADVICE

To me, hypermiling is an intellectual exercise with a certain amount of personal risk (getting shot or bunted off the road by drivers trying to actually get somewhere).

Truth!

I imagine it's fun to some, but in every case, my goal is to get there with as little delay as possible - and to have any possible fun driving. That means traveling speed limit +4 MPH and not slowing down for corners - straights are no fun, all the challenge is in the corners.

Pretty true, but be safe with those corners

I'd like to see more diesels in the US but manufacturers seem convinced the US public won't buy them.

Joe Q. 'Mericun is pretty ignorant when it comes to vehicles . That's why we don't get many nice ones.

Notes:

- Coasting in neutral is harmless to some automatic transmissions and all manual transmissions, but it reduces your control of the vehicle and therefore increases your personal risk. Some older automatics will be damaged if you coast in neutral. Do your homework on your individual vehicle.

Pretty spot on.

- Do not inflate tires to pressures higher than the max rated on the sidewall for sustained driving. If you're in an autocross or something like that, you can run them higher for that short period, but heat buildup over time can destroy tires when they're seriously under or over-inflated.

Truth.

- If you're going to drive for ultimate gas mileage, for gawdz sake get OUT OF THE WAY of other traffic. Don't be an obstacle!!

Truth.

- Trying to draft behind semis is a good way to get DEAD. Don't do it. Ever. At the very least, you will have one monumentally pissed-off semi driver, and you don't want a vehicle with 18 times your weight mad at you.

And very true.

Just today I got a darn near front row seat of somebody really messing themselves up today. [Invalid or Expired Link Removed] Be safe out there, that vehicle had been smashed front and back like a cheap p**n star. Still don't know the individual's outcome but it didn't look good when nobody from the responders (all 20 of them) looked to be in a hurry, even the professional kind of hurry.

Peace,
Greg

 

[iamlowsound]

There's no way he's getting over 30mpg in a F150 - look on Ford's site, the best rated mpg is 17/23 for a 4x2 V6.

That's another thing I hear all the time, people greatly exaggerating their mpg...

Look at the specs for the 2011 F150 FX4 EcoBoost. I have driven it quite a bit (we car pool together) and he regularly gets 9.5L/100km, which is 30mpg.

lowsound

 

[David Jayne]

In relationship to wind resistance yes, but if the object is slippery enough in the wind it will not need as much power at x speed to maintain that velocity compared to another object with a higher drag coefficient.

Irrelevant. We're talking about ONE vehicle, at different speeds. No matter how slippery it is, it takes 4 TIMES THE POWER to double its speed. This is physics.
Unless the car requires equal or LESS throttle to go faster(unlikely), it will use more fuel to go faster, period. As will any vehicle.

http://ecomodder.com/forum/showthread.php/tested-speed-vs-mpg-2008-corvette-z06-505-a-9841.html

 

[Let It Fall]

Wow...ever studied an internal combustion engine? So much mis-information. Best bet, leave the vehicle in gear and quit whining about your gas mileage.

what didn't make sense? The injectors being cut off? If you didn't know that please stop being so cocky..

 

[aborgman]

Hunter WHO?? Google turns up nothing related to tires, and 75 is racing bicycle territory. I've never seen an automobile that required 75 psi in it's tires.

Hunter S. Thompson. Author of "Fear and Loathing in Las Vegas"

But fifty pounds each didn’t help the cornering, so I went back a few hours later and told him I wanted to try seventy five. He shook his head nervously. “Not me,” he said, handing me the air hose. “Here. They’re your tires. You do it.”

“What’s wrong?” I asked. “You think they can’t take seventy-five?”

He nodded, moving away as I stooped to deal with the left front. “You’re damn right, he said. “Those tires want twenty-eight in the front and thirty-two in the rear. Hell, fifty’s dangerous, but seventy-five is crazy. They’ll explode!”

I shook my head and kept filling the left front. “I told you,” I said. “Sandoz laboratories designed these tires. They’re special. I could load them up to a hundred.”

“God almighty!” he groaned. “Don’t do that here.”

“Not today,” I replied. “I want to see how they corner with seventy-five.”

He chuckled. “You won’t even get to the corner, Mister.”

“We’ll see,” I said, moving around to the rear with the airhose. In truth, I was nervous. The two front ones were tighter than snare drums; they felt like teak wood when I tapped on them with the rod. But what the hell? I thought. If they explode, so what? It’s not often that a man gets a chance to run terminal experiments on a virgin Cadillac and four brand-new $80 tires. For all I knew, the thing might start cornering like a Lotus Elan. If not, all I had to do was call the VIP agency and have another one delivered … maybe threaten them with a lawsuit because all four tires had exploded on me, while driving in heavy traffic. Demand an Eldorado, next time, with four Michelin Xs. And put it all on the card … charge it to the St. Louis Browns.

 

[Pilgrim]

It's really not a good idea to ever take a vehicle out of gear while driving. As noted earlier, it's illegal in some states. It reduces your control of the vehicle - you can't accelerate or use the throttle to steer around traffic. It reduces your braking power by eliminating engine braking, which can lead to a vehicle going out of control on a steep downhill...and at the very least, causes increased wear on the brakes by requiring them to be used more often and more firmly.

I know people do a variety of creative things, but I suggest that in the quest to increase gas mileage, it's wise to balance a MPG or two against the personal risk you cause to yourself, the potential for vehicle damage, and the potential for causing road rage or frustrated driving behavior in others who you might be obstructing.

Given that you're being safe, not causing problems with other drivers and not obstructing traffic, enjoy yourself and see what you can achieve.

And Hunter Thompson is the very LAST person in the world I would turn to for advice on tire pressures. I've been through the Bob Bondurant School and the Washington State Patrol Police Instructors school, and in both cases tire pressures were discussed at length. Don't inflate your tires over the maximum rated pressure on their sidewalls...you can easily cause tire failure. 75 PSI is, to be candid, f***ing insane!!!!! (Of course, so was Thompson more than a little bit of the time.)

 

[slaps76]

Look at the specs for the 2011 F150 FX4 EcoBoost. I have driven it quite a bit (we car pool together) and he regularly gets 9.5L/100km, which is 30mpg.

lowsound

I did, and it's worse than the 3.7, rated 16/22.

 

[Pilgrim]

If you're driving a pickup, you are not driving it for gas mileage. Despite the efforts of Detroit to mitigate gas mileage, trucks will continue to have the worst gas mileage of any vehicles on the road. Soon they'll all be V6 models except in the 1-ton and up class, and their mileage will still be poor.

If you drive a pickup because you like them and want a pretty he-man toy (the fact that there's never anything rolling around in the bed scraping it up is usually a giveaway of this condition), either shut up about its gas mileage or sell it and get a car. You don't need it, so you're a volunteer for bad gas mileage.

If you need a pickup for your work, you know it and you're not likely to complain about what is simply a reality of owning the vehicle.

I really liked my '93 F-150 with the captain's chairs but it got 12 MPG and I didn't need it, so I sold it.

 

[kanonfodr]

Irrelevant. We're talking about ONE vehicle, at different speeds. No matter how slippery it is, it takes 4 TIMES THE POWER to double its speed. This is physics.
Unless the car requires equal or LESS throttle to go faster(unlikely), it will use more fuel to go faster, period. As will any vehicle.

But if it's going (Big Word Ahead) Proportionally faster while using proportionally less fuel, it's getting better gas mileage. Gas mileage - Miles traveled in relationship to a unit of fuel used. If we assume 55 mph is our starting point, 90 MPH is 1.6 times faster than 55mph. If we are burning 2 gallons per hours at 55 mph (approximately 22.5 miles per gallon gas mileage) BUT burning less than 3.2 (1.6 times 2 GPH at 55mph) gallons per hour at 90 mph then we are traveling further on a smaller amount of fuel over time and distance.

what didn't make sense? The injectors being cut off? If you didn't know that please stop being so cocky..

Your injectors don't get "cut off", that would cause a (Technical Term Ahead) Bad Thing as your engine cuts off completely. Your motor stops Motoring. Instead, Flow is reduced to idle when you lift off the throttle and that's why your rpms drop (along with the flywheel/flexplate being disconnected from the drivetrain when you place your transmission into Neutral)

I'm not cocky, I'm trying to keep people from getting killed by stopping the bad info being passed around this thread like genital warts in a locker room.

Hypermiling isn't necessarily a bad thing but right now it's a case of the Self-Righteous preaching to the Ignorant, it seems. Believe me, if there was a safe way to squeeze extra MPGs out of my Jeep, especially with gas almost $4 a gallon here, that wasn't cost-prohibitive for me I would jump on it in a heartbeat. But unfortunately 90% of the vehicle operators on the road are a danger to myself and others because They Don't Care about me, or you, or anybody else. And a lot of hypermiling babble by those preaching it isn't based on any great understanding of what actually goes on under the hood of a modern vehicle or the physics of what they are doing and why they shouldn't.

I probably sound a little paranoid or something, but I've got a healthier bit of training and practice than the average driver will ever have including track time with the California Superbike School. I've got folks I chat/ride with and really look up to/ model my driving on that have stood on podiums in the racing world. On the track: Monsters! The lot of them. On the streets? Completely focused and conservative, because it's way more dangerous on the streets than it will be on almost any track. I'm also licensed for 45-passenger commercial busses. That was actually some of the hardest training I've ever experienced behind the wheel

And ya, I've had my crunches, crashed, and tickets. I've had my license suspended. Guess what, I got smart. Nowadays people at work request me to drive them when they are traveling on official business. Word's spread, not by myself but by others. Because they know I'm a good, safe driver. Am I the best? Heck no, I know that much. But I do understand way more than the average operator about what's really involved in safely operating a vehicle. I read accident investigations and see what the pros say about accidents. And I try not to commit those same mistakes.

So of course, when I see folks posting information that's clearly wrong according to either Physics, Mathematics, or Common Sense I feel a bit obliged to step in. Not trying to be the butthole but people die on the streets every day and I don't want to read about a member of a community I like (TB Brethren) getting messed up in what could have been a preventable collision.

Hunter S. Thompson. Author of "Fear and Loathing in Las Vegas"

Ah, Touche

Peace,
Greg

 

[Let It Fall]

Your injectors don't get "cut off", that would cause a (Technical Term Ahead) Bad Thing as your engine cuts off completely. Your motor stops Motoring. Instead, Flow is reduced to idle when you lift off the throttle and that's why your rpms drop (along with the flywheel/flexplate being disconnected from the drivetrain when you place your transmission into Neutral)

I'm not cocky, I'm trying to keep people from getting killed by stopping the bad info being passed around this thread like genital warts in a locker room.

Well im sorry to say your WRONG.

For coasting in gear, a later-model vehicle with a fuel-injected engine will realize more gains from the burn and coast technique than older carbureted engines because the engine control units in most fuel-injected engines will cut fuel to the engine when the car is in gear, the throttle is closed and the engine is running faster than idle speed. This is sometimes referred to as "deceleration fuel cut off". This will often engage while a car is coasting down a hill and is common in both automatic and manual transmission vehicles, although the particular engine speeds at which it will engage vary.

Look up fuel cutoff deceleration. Its standard on many newer vehicles, now STOP BEING COCKY your wrong.

 

[Sonic_Death]

I'm going to steer clear of any arguments with this thread, but I'm willing to throw in my own personal experience.

I've heard the term hypermiling before and I guess I "practice" it, but it's more of just the basics and part of my driving style now.

I don't think I do anything crazy, and it certainly is never dangerous for myself or others. Simple things. I try not to brake excessively; if I am coming up to a red light I take my foot off the gas immediately and try to just coast naturally; I don't accelerate too quickly and try to keep a steady mph when possible.

I also tend not to run the heater, and I don't have an A/C in my car so that's not an issue. Just because it's annoying, I usually avoid having my windows open on the highway, although on some hot summer days I have to do it so I'm not toasting in the car.

There are a couple things I should do more often though, one specifically being checking my tire pressure. That's just a general safety issue, but it obviously helps with your fuel economy as well.

I have a friend who insists on putting his (automatic) car in neutral at every red light. He claims it saves on gas, but I can't see it really doing enough to warrant the wear on his transmission. Who knows... I think I read an article a year or two ago about some people in Japan turning their cars off at some red lights, and they have a countdown for when the light will turn green again. Supposedly they'd save more on gas by turning their cars off than idling. I may be completely wrong with that, but that's what I remember reading.

 

[Pilgrim]

Well im sorry to say your WRONG.

Look up fuel cutoff deceleration. Its standard on many newer vehicles, now STOP BEING COCKY your wrong.

Many of us don't drive "newer" vehicles. My family fleet is an '83 280ZX Turbo, a '91 Camaro convertible, a '94 BMW 325i and a '99 Jeep Cherokee. Only one of them is under 150K miles. And only the Jeep is likely to be replaced within the year - with another used vehicle.

In fact, the used car market is very healthy, and the average age of vehicles in the US is now 10.8 years. (Polk Auto Data Service, cited in USA Today 1-17-12.) Those cars don't have "fuel cutoff deceleration."

Even many new vehicles don't have "fuel cutoff deceleration."

Generalizing about vehicles has its hazards. "Your (sic) wrong" yourself.

Grammar help: http://www.wikihow.com/Use-You're-and-Your

 

[Let It Fall]

I'm going to steer clear of any arguments with this thread, but I'm willing to throw in my own personal experience.

I've heard the term hypermiling before and I guess I "practice" it, but it's more of just the basics and part of my driving style now.

I don't think I do anything crazy, and it certainly is never dangerous for myself or others. Simple things. I try not to brake excessively; if I am coming up to a red light I take my foot off the gas immediately and try to just coast naturally; I don't accelerate too quickly and try to keep a steady mph when possible.

I also tend not to run the heater, and I don't have an A/C in my car so that's not an issue. Just because it's annoying, I usually avoid having my windows open on the highway, although on some hot summer days I have to do it so I'm not toasting in the car.

There are a couple things I should do more often though, one specifically being checking my tire pressure. That's just a general safety issue, but it obviously helps with your fuel economy as well.

I have a friend who insists on putting his (automatic) car in neutral at every red light. He claims it saves on gas, but I can't see it really doing enough to warrant the wear on his transmission. Who knows... I think I read an article a year or two ago about some people in Japan turning their cars off at some red lights, and they have a countdown for when the light will turn green again. Supposedly they'd save more on gas by turning their cars off than idling. I may be completely wrong with that, but that's what I remember reading.

these are all great things. neutral at a stop does save gas because your engine has less load. There is a load when you stop thats why your car moves forward when the foots off the break. You can use the heater it really doesn't loose much other than the small load on the alternator of the fan blowing and slight engine heat loss but your radiators getting rid of the heat either way.

And in japan? People do that all the time on the ecomodder forum. Many of them have do EOC. They kill their engine when coasting, with a button they install or just via the key, and either start it while driving or put it in gear and come off the clutch to start. I wouldn't do it but. Its fairly common among hypermilers.

 

[Let It Fall]

Many of us don't drive "newer" vehicles. My family fleet is an '83 280ZX Turbo, a '91 Camaro convertible, a '94 BMW 325i and a '99 Jeep Cherokee. Only one of them is under 150K miles. And only the Jeep is likely to be replaced within the year - with another used vehicle.

In fact, the used car market is very healthy, and the average age of vehicles in the US is now 10.8 years. (Polk Auto Data Service, cited in USA Today 1-17-12.) Those cars don't have "fuel cutoff deceleration."

Even many new vehicles don't have "fuel cutoff deceleration."

Generalizing about vehicles has its hazards. "Your (sic) wrong" yourself.

umm. im wrong because I said...

Many newer cars kill the injectors when the vehicle is a. In gear b. no foot on accelerator c. Rpms over a set point (1000 Rpms in my jetta).

did i say all or even most? nope.
By newer i dont mean 2012. This system can be found in a 1994 sentra a economy car. And since only 38.3% of americans drove a 10 year old or older car in 2001, and that
honda accord
nissan altima
toyota camry
honda civic
are some of the most sold cars and they use this Im gonna change my statement.. NEARLY ALL MODERN CARS USE THIS.

 

[David Jayne]

But if it's going (Big Word Ahead) Proportionally faster while using proportionally less fuel, it's getting better gas mileage. Gas mileage - Miles traveled in relationship to a unit of fuel used. If we assume 55 mph is our starting point, 90 MPH is 1.6 times faster than 55mph. If we are burning 2 gallons per hours at 55 mph (approximately 22.5 miles per gallon gas mileage) BUT burning less than 3.2 (1.6 times 2 GPH at 55mph) gallons per hour at 90 mph then we are traveling further on a smaller amount of fuel over time and distance.

Greg

OK, but since that NEVER happens, what's your point?

 

[kanonfodr]

Well im sorry to say your WRONG.

Look up fuel cutoff deceleration. Its standard on many newer vehicles, now STOP BEING COCKY your wrong.

Curious about decel fuel cut-off, AFM/DOD - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums - Camaro5.com

It's not a complete cut-off, just a really choked mixture it seems. I put over 100 miles on a fairly late-model F-150, didn't notice the engine just dying out on it either. I've known that hybrids cut their engine off when programmed to, and the newer BMWs will shut off at a stop (much to Jeremy Clarkson's dismay on one episode of Top Gear). But absolutely no fuel flowing while the vehicle in motion scares the bejeezus out of me and I hope my next vehicle doesn't do that. Either way, we're both partly right.

Peace,
Greg

 

[kanonfodr]

OK, but since that NEVER happens, what's your point?

What never happens?? Theoretical my math may have been for that exercise, but it's completely realistic in many vehicles.

Peace,
Greg

 

[David Jayne]

What never happens?? Theoretical my math may have been for that exercise, but it's completely realistic in many vehicles.

Peace,
Greg

Kindly name one, with supporting data.

 

[Rob22315]

Well im sorry to say your WRONG.

Look up fuel cutoff deceleration. Its standard on many newer vehicles, now STOP BEING COCKY your wrong.

My ancient 1988.5 Suzuki Samurai had a fuel cutoff valve which operated during deceleration. It's nothing new. Nowadays, its probably just built into the software, no extra valve required.

 

[kanonfodr]

Kindly name one, with supporting data.

That I can't offer you right now, because I must've forgotten my camera that day I was getting 21+MPG in my Mazda pickup truck over 7 years ago doing well over the speed limit. The closest I have right now is this:

[Invalid or Expired Link Removed] See the side bar in the links.

Part of the problem is that few people are willing to admit and brag about their speeding. And not many formal studies are conducted of trying to find the most efficient speed for any given vehicle, regardless of agenda.

Peace,
Greg