Hypermiling - is anyone trying it?

[StorminN]

Is anyone trying it? The basic stuff makes sense... drive slower, inflate your tires to the max rating, remove unused belts (like AC belts here)...

But some of the stuff is counter-intuitive to me... for instance, I assumed driving in a higher gear (lower rpms) would use less gas... but if you read the BSFC stuff, it says medium to high rpm's and wide open throttle is actually more efficient!?! This is a big part of how the Prius and Insight hybrids get better mpg's.

Interesting:
General Introduction to Hypermiling

Really interesting (I'm going to wire this up):
DIY Fuel Rate Meter

Really really interesting:
Brake Specific Fuel Consumption

My 1991 Subaru wagon (1.8L engine, 5-speed) is currently averaging 26mpg (last five tanks)... I'm going to try some of this out and see if it makes a difference...

-Norm.

[Warbird]

Driving slower may help but I've found that what makes the largest difference is in how you accelerate.  I was one of those guys who would mash the pedal down to get up to the speed limit as fast as possible.  This consumes a *lot* more fuel than if you take yer time getting up to speed.

[Greg]

Didn't read your links, but...

It works. I've done it.

My subaru has rated mileage of 20/27, but I can easily average over 30 mpg in mixed suburban/highway driving conditions.

By carefully driving I'd say anyone could increase their mileage 25%. Single biggest fuel waster, as someone already said, is jackrabbit starts. Also, I was surprised to find I'm better off with AC on the windows shut then the windows open - due to air resistance, esp. at highway speeds.

The downsides/reality of course are significant:

1) if you are in a rush to get anywhere, forget it
2) get used to everyone riding your bumper, now that you drive like a granny..
3) don't get complacent/fall asleep with that cruise control
4) its not a good way to impress your date!

:D
Greg

[PC-Urban-Sawyer]

I hypermiled once, back in the early 70's...

I was coming back from Reno, Nevada going to Vallejo, California. I'd lost all my cash and didn't have a credit card. I didnt' have enough gas in the little Austin Healey Sprite to drive all the way back to the Navy base. Once I made it past the peak of the Sierras on Interstate 80, I put the transmission in neutral and turned off the engine. Must have coasted at least fifty miles deadstick. Got a little scary a few times, that's the fastest that little car ever went, with or without power...

Made it almost 200 hundred miles on less than a half tank of gas... I probably averaged about seventy mpg on that trip...

[sawguy21]

 :D :D :D :D Did the car need new brakes shortly after that? I did something similar one night trying to nurse a Ford pickup to a gas station but it was a hairy ride down the mountain with no compression braking. I needed the engine running for the p/s and p/b.
I am certainly more conscious of my driving habits with the current price of gas. I slow down and drop out of o/d on the hills and smooth acceleration at the lights. We are looking at a small travel trailer for the summer but motels might be a better option.

[StorminN]

Driving slower may help but I've found that what makes the largest difference is in how you accelerate.  I was one of those guys who would mash the pedal down to get up to the speed limit as fast as possible.  This consumes a *lot* more fuel than if you take yer time getting up to speed.

Warbird, this is exactly what I don't understand... granted I read it only once, late last night... but the gist of what I got from the BSFC article is that they're saying you're better off driving with the throttle wide open, shifting sooner... the engine runs more efficiently at, say 2,000 rpm's than it does at 700 or 4,000...

I've got a Fluke multimeter with % duty cycle, I'm going to tap my injector wire and see what it reads like in my "normal" driving style...

-Norm.

[Bibbyman]

From all the trips we've made with our 3500 Dodge in the past year,  I've learned that I get better gas mileage by not using the cruise control – especially when loaded or in rolling hills, etc. 

The Dodge has an automatic transmission with overdrive and some kind of lock in feature.   As soon as there is much need for torque, the lock kicks out and then soon after the overdrive kicks out.  Loaded on the toughest grades, it will kick down and gear and the engine hits about 4,000 RPMs.   But if I don't used the cruise control and kind of let it build up some speed going down a grade,  I can generally feather it back on the next rolling hill so it don't change gears nearly as often.   

[breederman]

I gain about 10% on my daily rounds by watching my starts and stops, holding, speed down,etc.  If I get busy and in a hurry mileage will drop sharply.  I check my mileage every fill up{1 1/2 to 2 days}  it helps keep me focused.

[Left Coast Chris]

Bibby,  our 2007 1500 Dodge 4X4 has a tow/haul button on the end of the shift lever.  That makes it not kick down to the lower gear as easy but also seems to keep the rpms in the 2500 range when towing in hilly terrain.  It will let it kick into overdrive to about 1500 rpm if on a complete flat and the load is not too heavy.   I never tried the cruise control when towing or in hilly terrain.  I love the transmission though.   You usually can't even tell it is shifting it is so smooth.

[Handy Andy]

  I have an old Toyota pu that I use for running around, just use the heavier trucks when I need to haul or pull a trailer.  Have found that I can coast quite a bit if I work at it.  Yeah, even the grannys get sore when you coast the last 1/2 mile before you turn a corner.  But it saves gas.  Funny how now they don't pass like drivers used to.  I can coast the last mile home, and very seldom anybody passes. 

[fencerowphil (Phil L.)]

The techniques do work, but it does increase my travel time
a lot.  Seldom do I find traffic conditions which allow me to do it.
I travel a lot of two lanes and it seems like all the chalk and log
haulers on my bumper are runnin' empty and haulin' buggy!

[Toolman]

I agree with Bibby,

I have an F-250 Powerstroke diesel and get lousy mileage using criuse control on hilly terrain. I drive 28 miles to work and averaged 19 mpg with cruise using scan guage. Without cruise on same route I'll easily average 24mpg.

[Ron Scott]

Cruise control isn't efficient on hilly terrain, only use it on flat running.

[Fla._Deadheader]

  Ed and I used to watch the Boost gauge, on the Dodge Cummins. We ALWAYS got better mileage than using the Cruise control.

[Ironwood]

Does coasting down to my storage area on the forklift count? I shut her off and cruise down then power up for the trip back "up" the 3% grade.   Those old Continental 4 cylinders SUCK the gas. They used them in just about everything.

Ironwood

[StorminN]

Ironwood,

I would say that counts!

-Norm.

[StorminN]

Update -

After trying some of these methods (mostly the driving-in-a-higher-gear, more open throttle method) and removing the roof rack (less drag) from my Subaru wagon, for my last tank I got 27.2 mpg, as opposed to 25.0 mpg, which was my average for the five tanks before then. This is an improvement of 8.8%. Granted, this is just one tank full, but the results are promising!

Now it's time to give the old car a tune-up...

-Norm.

[happyj]

i have been trying this for the past couple of months. I keep my foot out of it, coast downhills, start off slow. I have always shifted pretty low so that has not changed but, i get 44mpg up from 40mpg. I can not convince myself to slow down for the 14 miles of freeway (65) i have a mental block with it. I drive 38 miles each way and only use the car for commuting. I have a 91 corrola that i want to do something on the electric car front. I want a sawmill more though at this moment.

[StorminN]

I have always shifted pretty low so that has not changed but, i get 44mpg up from 40mpg.

I say 10% is nothing to shake a stick at!

-Norm.

[fencerowphil (Phil L.)]

I have always wondered why someone had not come out with what I call
"soft cruise control."  In effect, it would do hyper-miling for you on mildly
hilly terrain.  The amount you would  bog down would be a user-set-variable,
and would be matched by a down-hill gain in speed.

Seems like it would save about 6-8% over using standard cruise on hills.

[farmerdoug]

It looks like you may be slowing down on the freeway too.  They are talking in Congress of reducing the freeway speed limit to 55 mph again.

[Ironwood]

Congress, I'd say leave us alone, Thanks. For those w/ enough cash to burn let'em go 80. Let economics rule. What next, tell us how big our yards should be?

I have seen peoplpe slowing down everywhere, economics will force behavior change.

Ironwoood

[fencerowphil (Phil L.)]

Congress has to look as if they are "doing something," especially this time
of the election cycle.   I also hope they leave the speed limit alone.  Hyper-miling is not
very effective on an interstate, but you sure can't let gravity work for you a
bit, if you can't get your speed up on those down-hill sections.

[DanG]

Some cruise controls are "softer" than others.  On most of them, you are best off to stay away from that resume button until you get it back up to speed.

[Bill]

It looks like you may be slowing down on the freeway too.  They are talking in Congress of reducing the freeway speed limit to 55 mph again.

You sure hit a sore spot. I think there's a rant coming - might want to ask the little folk to leave the room . 

Iffen those folks we pay to sit there in DC wanted to conserve fuel they'd have done some or all of these
1> timed the lites - round here they turn red when you get to 'em - bothered me so much I started counting ( I'm older I'm allowed to be cantankerous now and then ) I get 6-8 red lites for every 2-4 green ones. don't seem right. They do time * *   one  * * road. But it was that way when I was a kid - no joy there
2> get rid of toll roads. I'm tired of stopping for tickets and waiting in line to pay 'em . I'd say Epass was the answer but first they take their cut/profit, before it goes to the govt ( politicians friends/relatives for patronage jobs , before all the freebies and kickbacks - er travel junkets, campaign contributions ) before whatever's left goes to fixing roads. And since we already pay at the pump a liquid fuel tax to build and fix roads they be double dipping.
3> there's lots of european versions of cars ( from american companies ! ) that get way better mileage - if epa would let them in. diesel mid sized cars that get 50+mpg and diesel vw's that get 80+mpg. EPA says diesel are polluters - 'scuse me but they seem to miss the benzene, micro pm's, co2, voc's and other toxins coming from gas. Seems they think some toxins don't make you as dead as the other toxins - just ask anybody that's spent an hour or two in a closed garage with the car running .
4> roads are bad in winter for the weather but in the summer - they rip them up for construction. Delay thousands and thousands for hundreds. I think it should be required that for every lane they take out of service they need to put a temporary lane in service - sorry I know it means less rebuilding but it just doesn't make sense to me to have all those folks just sitting in their cars - leastways till we get past all this oil price shock.

No sense in my gettin riled  and apologies to those that didn't  want to hear this much - but if govt wants to reduce demand maybe they should stop interfering .

OK hypermiling - I seen some web sites where they also use a pulse and glide - a little over the limit then coast to under the limit. They're claiming up to ~20% better mileage. The extreme ones will try to draft - way to scary and far as I recall - we'd call it tailgating .

[Toolman]

This congress is a joke. This country has the potential to be off foreign oil completely and have diesel vehicles that get 50+ mpg. If people don't vote these pathetic clowns out of office then I quess we get what we deserve. We all know who were talking about. Pelosi, Reid, Schumer, Hagle, Boxer, Casey, etc. These jerkoffs are killing us one inch at a time. I'm sorry if I offended anybody, but, their voting record tells it all on energy independence. Same with Obama, keep this Marxist goof away from White House.

[Beweller]

It took me a while to realize the subject was "hyperMILing", not "hyperMILLing".

In the good old days (carburetored engines, manual transmissions) the rule was to accelerate at wide open throttle in high gear from the lowest speed possible without bucking, to some higher speed (35 mph was frequently suggested--probably because the aerodynamic drag became significant at about that speed--, shut of the engine and coast in neutral to the lower speed, restart the engine and repeat.

The engines displayed the best specific fuel consumption at WOT over a considerable speed range, from just above idle to just below the speed at maximum power output, so this procedure maximized milage.

With automatic transmissions, this approach is a disaster.  When you put the peddle down, the transmission does the equivalent of shifting into a lower gear.  This maximizes acceleration, but also maximizes fuel consumption.  For maximum milage, come compromise is needed, getting the maximum throttle opening while minimizing the down shifting.  I have never seen hard data concerning where this optimum lies.

I suspect this down-shifting is responsible for the claim that cruse control leads to poorer milage on hilly roads.  The @#$% thing does tend to put its foot in it on significant hills.  And then overshoot at the top.

"Hypermiling" used to be (maybe still is) a competitive sport.  My memory says that there were guys that achieved--or maybe got close to--100 mpg.

Things that help:

     Weight:  Minimize.  Remove unused seats, floor mats.  Do you really need a spare tire?  And that full tank of gasoline?  Would a smaller battery suffice?  And tires should be the minimum width (weight) you can live with.  Agin, in my time, tax on tires was based on weight, so the lowest tax was the lowest weight.

     Tires:  Inflate to the highest pressure you can live with.  On a truly smooth surface, rigid is best.  With some surface roughness, my guess is that there will be an optimum inflation pressure, but this is going to be pretty high for typical roads.

     Lubrication:  The lightest, least viscous you can live with.  Remember you are going to have only light loads on your equipment.  Include gear lubes.

     Steering:  Turns cause engine power to be used grinding rubber off of your tires, and goes to heat the tires and road surface.  Avoid twisty roads, steer straight.

     Anticipation:  Drive as far ahead as you can see.  Avoid stops, in fact any breaking.  Don't rush to get to the red traffic light.

I'm sure you can think of some more!

[Beweller]

I should add:

     Wind.  Do not drive into a head wind.  The effect is not averaged out by a round trip.  If travel is necessary, reduce speed.

     Temperature.  Do not drive in cold weather.  The increased air density has a significant impact on aerodynamic drag.  Again, if travel is necessary, reduce speed.

     Vehicle.  Small is better.  Low is better.  Look for minimum frontal area, minimum protrusions.  A smoothly sloped back is desirable.  Some of today's vehicles look as though they were intentionally designed for flow seperation and maximum base drag.  Their drag coefficient must be high.

Minimum protrusions--there may be a plus in some cases.  A protrusion may trip the boundary layer from laminar to turbulant, delaying flow seperation.  Roof bars suggest themselves.  Again, I have seen no hard data.

     Engine fan.  Remove blades, or for electrically driven fans, the entire fan/motor.  I drove a '39 Chevy for several years with fan blades removed.  Only two worrysome incidents--stuck in traffic on a Friday before Labour Day, And trying to help a motorist stuck in snow.  (You do need the water pump!)

     Air conditioning (vs open windows).  Neither.  I can recall driving across Indiania one August and not being able to decide whether it was better with the wndows open or closed!  I survived, and so can you, with the AC off and the windows closed.

[StorminN]

This congress is a joke. This country has the potential to be off foreign oil completely and have diesel vehicles that get 50+ mpg. If people don't vote these pathetic clowns out of office then I quess we get what we deserve. We all know who were talking about. Pelosi, Reid, Schumer, Hagle, Boxer, Casey, etc. These jerkoffs are killing us one inch at a time. I'm sorry if I offended anybody, but, their voting record tells it all on energy independence. Same with Obama, keep this Marxist goof away from White House.

Toolman,

Are you really blaming the US using foreign oil on the current Congress? I think it goes back a little further than that... maybe Reagan, maybe Nixon or before? I agree that we should be able to have efficient diesel vehicles, and for years have been frustrated that here in the US we can't buy the efficient, cool vehicles that I've seen in Europe, Japan, and elsewhere (even Canada!).

... and I believe this belongs in the "Stumping for Mike H" thread, but if you'd like to elaborate on how "these jerkoffs are killing us one inch at a time" and how McCain's energy independence policy is superior to Obama's, I'm all ears...

-Norm.

[Toolman]

I blame congress in general,

Look how many members of congress that have been in office for 20 + years, including McCain. They knew this was coming years ago. They all watched China and India grow by leaps and bounds. They watched world consumption grow year to year. Now, look at us. Our Congress is reactive not proactive. They can't or won't look farther ahead then the lobbyist that's standing in front of them handing them favors(money). How can you get off foreign oil without domestic drilling. The alternatives are years away, we need more oil on market to bridge that gap between now and then. I'M ALL FOR ALTERNATIVES. At least McCain is now for off-shore drilling, Obama is not. As much as some people want to deny this, affordable energy is what is needed for a vibrant economy.  It's foolish to expect more jobs and growth, but then not use our own domestic resources to feed that. Why send 700 billion dollars a year to OPEC nations, when that money could be spent on our own oil production. It does'nt make sense.  I stand by my comment whole heartedly, congress is loaded with corrupt goofs that are killing this country one inch at a time.

Why don't we have those neat European vehicles in this country? The EPA standards won't allow it.  Does'nt anybody congress recognize this?  Come on. If anybody thinks powerful members of congress are'nt being bought off, what more proof does anyone need. It angers me when I see good hearted members of this forum discuss the negative effects this oil situation is having on them. This country has so much potential to become clean energy independent and our so-called leaders are basically sitting on their hands blaming everyone but themselves. Their inaction to a problem that has been brewing under their elitist, arrogant noses for years. It's sad that a country like this has to have good guys talking about hypermiling. Would'n t it be fun talking about how great our sawmilling businesses are doing?   Sorry If I offended anyone. I just get frustrated watching all of this potential being thrown away by a small group of people that only want to satisfy their own self interest.

[fencerowphil (Phil L.)]

Alas!

I guess one reason I have been slobbering over solar power,
                                                                        wind power,
                                                                        ethanol stuff,
                                                                        thermal depolymerization,
                                                                        and other such insignificant stuff...

is that I ain't got no sawin' ta do rite now

:'(     :'(     :'(      :'(

See what happens when I am not able to saw:  I get all obsessive compulsive!

Beweller,
It's good to see somebody on here with enough years to know what they are talking about!

[StorminN]

How can you get off foreign oil without domestic drilling. The alternatives are years away, we need more oil on market to bridge that gap between now and then. I'M ALL FOR ALTERNATIVES.

Toolman, I agree with most of your last post... but from the numbers I've seen, even the "plentiful" but controversial ANWR oil deposits would only last about 90 days at the USA's current rate of consumption... so it's my opinion  ;D that the answer lies more in the realm of "let's all use less" than "let's drill more"...

-Norm.

[Toolman]

Norm,

I agree we should use less. But I feel we should do everything. Drilling, conserving, alternatives. I know we have a great potential to be totally independent from foreign oil. I hate seeing all this money being sent to nations that are sponsors of terrorism and human rights violations. As far as ANWR goes, I hear so many numbers on the amount of oil there, but do you think oil companies would invest that much money into an area that has only a 90 day supply? I suspect there is a substantial amount there for them to want to drill there.

You know Norway is one of the most pro-environmental countries in the world. They have been off-shore drilling for years without a single spill. During Katrina, Not one drop of oil was spilled from drilling rigs during that storm. I am pro-environmental, but the technology exists to do these things in a responsible manner. I would rather see a 2,000 acre parcel of land being used to extract oil then the same amount of land being used as shopping malls, housing developments,etc.- blacktop jungles!! I would like to see us do it all. Wind, solar, biofuels. There is a thread here about algae as a fuel source. That was interesting and promising.  I feel alot of environmental extremist feed the the public lots of misleading info and they do in fact influence alot of members`of congress. This special interest garbage is really holding us back.

Take care Norm

[barbender]

I tried slowing down with my 97 Dodge 3500 Cummins 4x4, been driving 55 mph and keeping my foot out of the pedal when accelerating, went from 21mpg to 23.6. I had to do some pulling with it after I filled last time, so this tank won't be as good. I read an article in one of the diesel pickup magazines where they took a two wheel drive dodge 3500 cummins and got 28 mpg with it. They had the mirrors folded in, no A/C and the windows up, a tonnaeu cover, taped the hubcaps up solid, modified it to run warmer (210 I think) etc.

[Toolman]

I read an article like that in Diesel Power Magazine. Pretty extreme, huh? I ordered a grill cover for my 250 powerstroke through Cabelas for winter. It really helps. It has adjustable air vents on it.

[DanG]

Since our car got crunched by a tree last week, we purchased a pristine 2000 Plymouth Grand Voyager.  We picked it up Wednesday evening, and I found that it has one of those mileage computers in it.  I've never had one of those before.  We had a little road trip already planned for Saturday, so we gave the "new" car a little 380 mile shakedown cruise, and I played with the computer all the way.  Unlike some of them, this one gives you an instant readout of MPG, as well as the average, so I was able to see the effect of the hills and accell/decell, etc.  I found that around here, where we have hills, at 72mph, the mileage would drop as low as 15mpg uphill, and up to 27mpg downhill.  I also noticed by the tach, that the car was downshifting in order to maintain speed going down the steeper hills.  I switched off the cruise control and found my level mpg and uphill mpg unchanged but the downhill mpg would go as high as 55mpg!  When we got about 100 miles east of here, the terrain flattens out, and the mpg settled on 23 at 72mph.  Then we got on a 2 lane road, still on flat terrain and travelling 60mph, the computer bounced between 26 and 27mpg.  65mph stuck it on 26, and 55 stuck it on 27.  The computer seems to be pretty accurate, as the average mpg agreed pretty closely with my true consumption figured at fill-up the old fashioned way.

My conclusion was that on this car, the cruise is killing me in these hills, because of the downshift.  On one further test on the way home this evening, I was cruising at 70 with nobody behind me as I approached my exit.  I just hit the cancel button about a half mile before the exit and let it coast.  The computer went up to 99mpg(max for the display) and remained there all the way down the ramp.

As a side note, when I gassed it up for the first time, I discovered that this car is equipped to handle E85.  That has some other wheels turning in this old bald noggin. ;D

[fencerowphil (Phil L.)]

DanG

I like to "feather," as some have called it, going UP hills.  The idea is to watch the
instantaneous mileage readout and lighten up my gas pedal just enough to keep
the mpg figure at no less than the average the vehicle gets.  (I shoot for a figure
of 20-22.)   On a considerable hill you will have to bog down to as low as 45 miles per hour,
but you can do it.  Then you have the chance to control your acceleration on the next
downslope to gain your momentum again.  It's a fun game.  These tricks make me
gain about 20% on average, but I often don't have the time to do it.

[Handy Andy]

  Here in Kansas, where it's supposed to be flat, we have a few hills.  I've found that on the way home from Salina, I can coast the last mile home, if nobody's coming, I can turn into my driveway a bit above 15 mph and make it into the yard and park without starting up the engine.  In my old Toyota pu.  I tried the wife's Miata, and it doesn't coast nearly as well, even though it has a 5 speed manual.  Jim

[Paschale]

I suppose it's short sighted of me, but I'd rather make fewer trips than think about all of those possibilities.  I drive the way I drive, and I like being aggressive when I need to be, and I still go 80 down the freeway because I don't like going slower.  I know I'm paying for it, but honestly, the changes that I've made have been to really think about whether I need to make a trip or not.  I'd rather drive less often, and still drive the way I drive than to do everything that guy says he does.  I'd go nuts thinking about all of that stuff!   ;D

BTW...I thought this thread said has anyone tried "hypermiLLing?"  I clicked on it to find out what "hypermiLLing" was all about.   :D

[Fla._Deadheader]

 

hypermiLLing

= Captain, Craig.  : ;D ;D ;D

[Tom Sawyer]

I'd rather drive less often, and still drive the way I drive than to do everything that guy says he does.  I'd go nuts thinking about all of that stuff!   ;D

Why not do both ???

[Paschale]

Well, some of the things I think I'll do naturally, like not putting the lead into it unnecessarily, but when you look at the link and the guy says things like "turn off the car before you put it in park" and all that other stuff, it just seems to get a little absurd.  Life's too short to worry so much about the price of gas going up--it's going to get higher the older I get, and it's just a fact of life that we all have to deal with.  I just think some of the guy's suggestions in that link are silly, that's all, and I know I will never do them. 

[DanG]

I know what ya mean, Paschale.  I've always driven rather conservatively, so there is less I can do to save gas than for a more aggressive driver.  Like you, there are limits as to how far I'll go.  I don't shut the engine off to coast, for instance, and I ain't gonna ride around in this heat with the windows up and no a/c. :  There are other things I will do, such as not using the cruise control in the hills, and sometimes I'll turn the a/c on and off as needed, but I'll mostly continue doing as I have been.  I've always found that driving with dignity and consideration for others is safer, cheaper, and a lot less stressful.

I actually got pulled over by a trooper for not having brake lights, once.  He was surprised that the lights actually worked just fine, I just didn't use the brakes. :D

[StorminN]

Speaking of hypermiling, is anyone out there running one of those "underdrive" crankshaft pulleys? A couple of guys at work drive Ford Rangers, and are talking about getting them for their rigs. They are a slightly smaller pulley in diameter, I guess the thought is that most of the accessories will run fine at a little slower speed... it's supposed to add back about 12 hp and some mpg...

-Norm.

[Beweller]

Regarding the performance of cruise controls on rolling roads, I find that my vehicle maintains  a steady rpm on gently rolling roads.  Thus the effective gear ratio must remain constant and the throttle opened while climbing.  I cannot envision any improvement in fuel economy I could make by manually controling a constant road speed.  However, on steeper hills, the engine rpm increases and the fuel economy must fall below the best possible.  Overall, I would expect some loss of economy on a rolling road as compared with a level road.

Some of the increased fuel consumption accompanying hill climbing and acceleration performs a needed function and cannot be avoided.  The potential or kinetic energy of the vehicle must be increased, and this requires the expendature of fuel.  However, this energy is recoverable--with some efficiency loss-- when descending or coasting (decelerating without braking).

For a theoretical vehicle weighing 3200 lb and having a brake specific fuel consumption of 0.0849 gal/hp hr (thermal efficiency of 25 percent), climbing a one percent grade uses 0.00765 gal/mile to provide the increased potential energy.  This may sound trivial, but if the vehicle gets 25 mpg on a level road, the economy will fall to 21 mpg on the grade.  On a five percent grade, 13 mpg.

Acceleration increases the kinetic energy of the vehicle.  An acceleration of 0.22 mph/sec is equivalent to a grade of one percent and has the same effect on fuel consumption.  Small accelerations/decelerations occur almost continuously in ordinary driving.

If the vehicle free wheels and the engine is stopped during descending/decelerating, the recovery of the potential/kinetic energy may be 100 percent effective.

[StorminN]

OK, so on this last tankful, I didn't try hypermile...   I just... took it easy... tried not to have sudden stops or starts, coasted down some of the big hills, etc. I got 26.5mpg, about 1.5 mpg higher than the average of the past six tanks.

I have removed the roof rack from my car and pumped the tires up to about 40psi. Other than that, I think part of the difference may be that I used Chevron fuel this time... the car seems to run better on this than on the Costco or Safeway gas... but who knows... the Chevron pump still says "May contain up to 10% ethanol", so maybe it's all in my head...

-Norm.

[Fla._Deadheader]

In the old days, 60's, I could NEVER get decent mileage using Esso or Sunoco.

  I believe what you say might be happening. Back then, the Tankers DID have the correct name on them, even if they DID all sell the same gasoline  : : :

[Furby]

Roof racks reduce mileage by 1 to 3 mpg based on my tests and talking to folks that have done the same sort of tests as I have.
Simply having 4 towers, with two 4' bars across was cutting my mileage about 1.5 mpg or a hair more.
My current roof rack system is in the 2-3 mpg loss area. :-\

[sprucebunny]

Here is the tool to teach you how to get the best mileage out of your car. It works on almost anything with a "OBDII" plug.
Can't wait to see if it works on my diesel  :P




This is an 'instant read' ... it also tells you trip averages and other stuff..... wish the car got 27 all the time 

It's a "ScanGauge II ". It will take a long time to save enough gas to pay for it at $170 but it can also reset codes from the computer.
My 1997 4runner has 240k miles on it and I can get 22+ in mixed rural driving in the summer.

The roof racks don't come off, though  ;D

[Ron Wenrich]

That's exactly like the one I have.  It will help show you where you waste the most gas. 

I also get to notice when some tanks get better mileage than others.  Could be the amount of ethanol in the gas, which is what I expect.  I also suspect they go over that 10% mark.

[arojay]

Something that few of us think about is airflow.  Over 50 mph, rpm has less effect than aerodynamics. 
Some things you can do about it are grill covers, take off roof racks when they aren't needed, even open windows can make a difference.  I'm sure there are others.  I have been driving as conservatively as I can remember to be, for quite a few years now.  I put on lots of personal miles and I've been trucking on and off for about 30 years.  It does make a difference to find the optimum speed for a given application.  Progressive shifting makes a big difference with manual transmissions too.

[shinnlinger]

Hi,

I, like a few of you, thought this was a hyperMILLING link and passed it by, but now this is interesting.

In NH there are plenty of hills to coast down so what they hey, slide the powerjoke into neutral.  I did shut the moter off once, but the ol one ton is a bear w/out power breaks and steering.  Maybe if I get the old Toyato on the road again....

NOw about this European Diesel thing.  I was in England a few years ago for a wedding and remarked at all the Diesels running around, particularly from Ford, and wondered WHY NOT IN THE US?  I mean if the have Diesel focuses there, why not here?  Its the same company and they already developed it. The Diesel jetta is a hot item here and has no competition.  I was also astonished to see the Maxi, Fords version of the Mercedes/Dodge/Freightliner sprinter (another hot US seller) was running on a frickin 2 liter Diesel (ok it may have been 4 liters, but way smaller than my 7.3).  Now this thing can go on the freeway just fine and haul as much as my F-350(If not more), but why isnt the small efficient diesel available here?  Shove that in an F-150 and away you go.  It is even ULSD compliant as that is what they have had over there for a while, so the bugs might even be worked out.

I dont think it is an EPA thing at all.  I recently read in FARM SHOW that the late '70's/early 80's chevy diesel 350 was such a POS that it turned Americans off from Diesels...gave them a bad name, but I think the real reason is this....You may have heard that Ford, in light of the recent slump in the truck and SUV are now going to import these European gems and start making them here in an effort to appeal to consumers.  I think this is a good idea, but a finacial analyst said even if they sell like hotcakes, the company may still be in trouble as the PROFIT margin is not as good as on an F-150 or SUV.

SO there you have it.  Those companies haven't been selling us these more efficient rigs because they are inferior, but rather because the dont make AS MUCH $$$ as the junk that we are now stuck with.

Rant over.

[Gary_C]

SO there you have it.  Those companies haven't been selling us these more efficient rigs because they are inferior, but rather because the dont make AS MUCH $$$ as the junk that we are now stuck with.

Unfortunately, there is more to it than that. In the US, we now have clean burn regulations (soot and particulate) on diesels that the EU has not adopted and which those European diesels cannot pass. In the US, the VW diesel just barely passed this last year and has had some reliability problems with that diesel engine.

This is also why both Ford and Dodge have had to come out with new versions of diesels in their light trucks. The old 7.3 diesel could not pass any soot emission regulations.

The heavy truck engines in the US, Cummins, Cat, Detroit and others have also had to comply and are having some problems with that clean burn technology. Unfortunately that latest technology clean burn engine gets worse fuel economy than its previous version.

So you have to blame the cleaner air you breathe as the real culprit.

[Toolman]

I love my scan guage. It saved me alot on fuel consumption by pointing out my bad driving habits. It is worth every penny!!

[shinnlinger]

Gary,

I appreciate that the NEW (2008) clean burn regulations complicate things a bit, but these diesels have been rolling around Europe for DECADES.

If They can make the big rig engines pass emmisions, they can make the small ones pass too.....

IF they wanted to

Yes there were problems with most of the Diesels making compliance this year, but like you said the VW engine PASSED.....barely, but it passed.