APLawrence.com -  Resources for Unix and Linux Systems, Bloggers and the self-employed

Hypermiling

A Google search for "hypermiling" will turn up a lot of links about saving gasoline by changing your driving habits. Most of them are just common sense: accelerate slowly, try to avoid stopping completely (slow down if a light ahead is red to give it a chance to be green when you get there), use your speed control..

Some of the suggestions cause great arguments. Windows down or A/C? Most everyone agrees that it depends on your speed; windows down is best at low speed, use A/C on the highway. But "low speed" of course depends on the aerodynamics of the vehicle, so the arguments about how much fuel is saved or wasted ensue.

Another controversial subject is coasting in neutral. Aside from possibly being illegal, some sites argue that this can damage an automatic transmission. Other sites say that with some vehicles, it's smarter just to coast in gear as the fuel injectors will actually shut off in that circumstance but will stay on idling if coasting in neutral.

Even more controversial methods have you coasting with the engine key shut off! That's definitely tricky and dangerous..

Our 2007 Subaru Outback was averaging a little more than 25 miles per gallon when gas prices started creeping up. I changed my driving habits immediately but had a harder time getting my wife to consider fuel economy. It wasn't that she didn't want to save gas, but that she felt that she was annoying people behind her by driving and accelerating slowly.

What changed my wife's mind was the MPG displays. Our car can show both current fuel consumption and average MPG over either of the trip odometers. When I'd take the car, I could boost the mileage up over 30 MPG, but her driving would drive it back down into the twenties almost immediately. Pointing that out aroused her competitive nature and she changed her mind and her driving habits. We now compete for the best mileage - I have managed to push it to 31.6 now and then, but she doesn't do quite as well so we hover around a 30.9 average now.. pretty strong improvement!

But her objections are true: people get ticked off if you creep away from a stop sign or drive less than 70 on the highway. I received more than my share of one finger salutes until I found the compromises that let me save gasoline without annoying people too much.

Accelerating slowly

This is probably the thing that will tick off a following driver the most. My compromise is to try to average it out. When there is no one behind me, I really creep, being extremely gentle with the gas pedal and taking my own sweet, fuel saving economical time getting up to speed. When there is someone behind me, I don't push it to that extreme - I don't make a jack rabbit start, but I don't creep along as I would if no one were behind. I figure my extreme economy measures at other times let me be a little bit wasteful here (though in a smarter world everyone would be driving gently and it wouldn't matter).

Avoiding stops

To anticipate and avoid stops, you need a big following distance. Staying far behind the cars ahead of you gives you the time you need to slow down so that you ran still be rolling when they start up again. Around town, that's not much of a problem: trailing cars don't get annoyed by my large following distance and don't usually get annoyed by my slowing down when a light turns red or people stop for a temporary obstruction and so on. The highways are a different story: when you leave a large following gap, somebody from another lane will usually fill it, forcing you to slow down more to get the gap back where you want it. This was one of my wife's objections: constantly slowing down to maintain the distance. She's gotten over that because of our mileage contest. After all, we're never in a hurry; why do we need to be driving fast?

Driving slowly

Because other people get very upset if you don't. There's nothing like driving the speed limit to attract a long line of tailgaters off the highway and to get people flashing their lights and waving their hands on the interstate. You can almost hear them screaming "Pull over, idiot!".

So we do. Saving gas isn't worth having some angry fool riding your tail lights. Around town, we'll pull right over and let them go by the moment they start crowding our rear bumper.. unless..

Unless there's someone in front doing the same thing. That doesn't happen often off-highway, but it's getting easier and easier to find other fuel conserving drivers on the highway. When you find them, fall into line. Maybe they are driving a little slower or just a tad faster than I would have, but that's OK. If the speed limit is 65 and I can fall into a line of people doing 62, I'm saving gas. I'd rather find a group doing 60, but this is OK for now, and because there is a line of us, nobody behind gets upset.

Other tips

The issue I had some difficulty with is removing unnecessary weight from the car. I like to have stuff I might need with me - tools, mostly, and of course these add weight; every extra pound being dragged along costs gasoline. I had to ask myself the tough questions: how many screwdrivers do you really need? Are you really going to need that cable testing kit today? How about that jug of windshield washing fluid?

We also just plain drive less. We plan our trips carefully - no more casually running out to pick something up. We wait until we have other reasons to head in that direction, and even get into detailed discussions of prices as opposed to the cost of gas: that gallon of milk is twenty cents more if I buy it here, but otherwise I have to go seven miles out of my way.. so buy it here.

Within our community, we use our golf cart or walk when we need to run down to the mail or the gym. Of course I had to do the math on that: the cart costs about 7 cents per mile for raw electricity, and about 75 cents per mile overall (maintenance, battery replacement). That's not necessarily better than using the car, but as gas prices continue upward, that stays fairly stable as the electricity cost is very small.

As to walking, I figure my base fuel cost is about 10 cents per mile and around 50 cents per mile over all. Of course my idling cost isn't a lot less and while there are several ways to cut consumption to zero, none of them are very attractive and some lack any ability to restart. The cost of walking should be balanced by its health benefits too, so I do that when I can.

I'm happy with the improvements we've made. We actually cut our gasoline costs by almost one third since we started - that's significant.



Got something to add? Send me email.





(OLDER)    <- More Stuff -> (NEWER)    (NEWEST)   

Printer Friendly Version

-> -> Save money by increasing fuel economy


15 comments



Increase ad revenue 50-250% with Ezoic


More Articles by

Find me on Google+

© Anthony Lawrence







Sun Jun 22 14:06:13 2008: 4358   ScottCarpenter


Good post. My little '98 Saturn has always gotten about 35 MPG in combined city/highway driving, and I haven't particularly tried to drive conservatively (although a speeding ticket a few years ago still has me watching my top speed more -- it's just not worth it to me to push the limit).

I do find it extremely irritating when people don't accelerate more quickly on freeway on-ramps. There'll be a 1/8 mile long ramp to a highway with a 65 MPH speed limit, and a lot of people are only going 45 MPH at the end when it's time to merge. I'm not sure how many of these people are conserving fuel and how many are just knuckleheads.

Other than that I'm trying to moderate my type A tendencies and just go with the flow. I still get impatient from time to time, but work hard at not following closely if someone is going slower than I want to go. That's one of my other major annoyances: tailgaters.



Sun Jun 22 14:39:26 2008: 4359   JohnB


These are all good points. I used the bus all day yesterday with my daughter, very successfully. It forced me to be in less of a hurry, and even though I try to keep myself from being in a rush, I don't always succeed.

Maybe, in addition to saving on gas, as more people take measure to save, more people will slow down. I wonder how many of the one-finger salutes you received were from people who were in a hurry for no good reason.



Mon Jun 23 14:50:13 2008: 4361   Dan


"We actually cut our gasoline costs by almost one third since we started - that's significant."

That's not significant--that's a miracle!

Are you sure you didn't mean usage, instead of costs?






Mon Jun 23 15:03:24 2008: 4362   TonyLawrence

gravatar
I mean costs - by cutting down on trips and increasing MPG



Mon Jun 23 17:37:03 2008: 4365   JonR


Applause from Kansas City! Car-free since 1982, when I was working I took the bus or, for several years, cycled the 5.2 miles each way. I racked up 14,000 miles of cycling in largely rush-hour traffic that way. I'm grateful for occasional rides in friends' cars but also concerned about fuel waste. Petroleum is not renewable -- not in our lifetimes.

I do believe slow acceleration on ramps is unwise. The ideal is to be as ready as possible to swiftly enter the highway stream, and to be stopped at the bottom of a ramp is an experience I remember all too well. Not good.



Mon Jun 23 19:42:38 2008: 4366   JamesFrancis


I really believe that Motorcycles/Scooters are the way to go (besides biking/walking of course). 50-100mpg is not uncommon, cheap to purchase, and insurance is around $100/yr. for mine. I have a cheap older motorcycle at home that I've had for years and I'm still getting 50mpg on it. You'd be surprised what you can stuff into a couple of saddlebags.



Tue Jun 24 14:06:50 2008: 4369   BigDumbDinosaur


I save gas by driving down hill as much as possible. <Grin>

Seriously, everything that Tony mentioned is valuable advice. As for the effects of speed on fuel consumption, consider that aerodynamic losses vary with the square of the speed. When factored in with other losses, you can assume that doubling your speed will result in an 8-fold increase in fuel consumption.

However, the mechanical efficiency of most cars with automatic transmissions deteriorates at lower speeds, as the converter clutch can't stay locked under those conditions, producing pumping losses. Experimentation with my geezermobile (a Merc Marquis) idetermined that the best fuel economy occurs in the range 58-73 MPH. Above that range, aerodynamics start to take their toll. Below that range, the converter clutch will unlock if ascending a grade, however slight, this due to the very tall gearing in the rear axle. At 70 MPH, the geezermobile can get about 28 MPG when on cruise control, not bad for a 3900 pound, four door sedan carrying a dinosaur. Oh yes, fuel consumption at that speed is lower with the windows up and the A/C on. Opening the windows causes a 2 MPG loss due to the extra turbulence.

Be sure to maintain your engine's state of tune. Periodically run fuel injector cleaner through the tank and occasionally accelerate full throttle to clear out combustion chamber deposits. Change the oil and filters regularly, and keep your tires properly inflated. The front tires on a front wheel drive car should be run at 2-3 PSI more than the rears. Use the opposite ratio for a rear wheel drive car.

Lastly, don't believe those EPA mileage estimates. They are derived from specific test sequences that don't reflect real-world driving conditions. If you see something about a fuel-efficient SUV or mini-van, you can be sure the manufacturer is talking about the EPA estimates. You can't circumvent the laws of aerodynamics. Anything with the high frontal area typical of an SUV or mini-van is not going to be very efficient at highway speeds. Unless you truly need such a vehicle (most of us don't), buy a sedan or coupe instead. Your wallet will thank you.



Wed Jun 25 07:14:15 2008: 4370   drag


I have a little moped that I used to drive to work. I even suped it up... The thing was designed to be limited to 30mph, but I can get mine up to about 45 or so on flat ground. (topped out at about 10mph going up a hill) I worked night shift so it was a pleasure to run it in the evening. Got better power when it was cool out, also. 60-100mpg. Fun to work on, fun to try to figure out ways to use what was laying aorund the house to keep it running.

Next level up is my motorcycle. A little 'Kawasaki 250 Ninja'. It's got a 'ninja' name, but actually it's just a little Japanese standard motorcycle designed in the 80's with a sporty-looking fairing. They starting making it in the early eighties, but just keep making it unchanged and is one of the most popular models sold every year. Mines a 2002, I think. Cheap and with _very_ good reliability. Car-like reliability, which is rare for a motorcycle or scooter of any type. The motor is now a old design compared to other things and it's a bit small for American-sized bodies, but it's still faster then 90% of the other vehicles on the road, by a good margin. (which is important, because it's what keeps me out of their way when things get a little scary) 40-60mpg. It's a very efficient and effective vehicle. (most motorcycles aren't)

Trouble is now that I live far from my work.. It's a good 25-30 minute commute without traffic. Plus I now work regular hours so I am out during rush hour. I tried riding my bike to work for a few weeks, but seeing 3 separate car accidents on the way home one day has pretty much made me call it quits on the motorcycle-to-work thing. A fender bender for a car would equal death and dismemberment for a motorcycle rider. Too many dipshits in SUVs, to many morons with a cup of coffee in one hand and a cell phone in the other going 20 mph over the speed limit on city roads.

The dirty-little-secret thing is, if you commute at highway speeds, a car will get you there faster and, if it's designed correctly, more efficiently. You see that motorcycles have a huge amount of drag on them. If you compare a average sports bike with a average small sedan you'll find that the car has a less drag on it... less effective frontal area, more aerodynamic. If people start making a very small car with a decent motor, preferably small motor, stick shift, and with a turbo, can (if done correctly) get better millage then a average (say 600cc and above) motorcycle at highway speeds.

Now for in-town stuff, like 20 minutes drives or less, then a scooter would be fantastic.. (200cc-400cc is about what you'd want) a ideal thing. Just as long as people are going to notice you before taking that chance with a left turn on yellow-turn-red. (You'll quickly learn to always be in the middle lane and to slow down before you get to the intersections (invariably pissing off the a-hole behind you). This gives you optimal reaction time.)



Wed Jun 25 16:09:11 2008: 4373   JonR


Seeing three accidents in one day would be sobering. On a big cycling forum I often advised beginning commuters worried by motor traffic to keep in mind that they are dealing with just one, or at most two, cars at a time, whether they're in New York, Hong Kong, or Kansas City. It's the only way to maintain the will to ride. Still it's undeniable that a motorcyclist, bicyclist, or commuter on a scooter is at a big safety disadvantage. In all those thousands of miles where I lost a little blood but thankfully didn't even break anything (except on my bikes), I found the most courteous drivers to be truck drivers -- I mean semis and big delivery vans. Maybe because they stand to lose the most (their jobs as well as their sleep at night) if they cause an injury accident; maybe because they just have more brains. But over all those years only two or three motorists of any kind ever showed impatience with me. I did obey the rules of the road and tried to give motorists the edge when appropriate.

The most dangerous thing for a cyclist is the possibility of getting "doored." Drivers don't look when getting out of their cars. And even if they did, a cyclist could be in a blind spot and unable to stop in time. (Just maybe, a loud warning device might help.) Virtually everywhere that bicycle traffic is permissible, cyclists are bound by the same laws as car drivers. That means the right to a place squarely in the traffic stream, but anybody who's ridden even one trip to work knows that doesn't work. In rush hour staying a safe distance from opening doors without getting enmeshed in the stream of often impatient drivers is the big thing to learn. In regions with foot traffic, daydreaming pedestrians are a great hazard. Cell-phone use has not improved things.

I think I kept cycling because I really wanted to prove it could be done. But there are other reasons for other people. I've been noticing more bicycles than normal on the roads here, in the last few weeks. And they haven't all been ridden by kids or even men and women in their twenties. I hope that, as this trend inevitably continues, since fuel prices are not going down anytime soon, if ever, novice cyclists will educate themselves so that the fragile goodwill between motorists and cyclists won't be eroded and lives won't needlessly be lost in the name of economy.






Sun Jul 25 12:47:44 2010: 8856   TonyLawrence

gravatar


I finally got my wife to slow down. It was gas mileage that got her to do it finally:

(link)



Wed Jul 11 12:00:30 2012: 11190   TonyLawrence

gravatar


The car is now 5 years old. The mileage has dropped to 27.6 to 27.9 - fluctuating between those two. We take very few highway trips, so that's decent.



Wed Jul 11 17:27:00 2012: 11194   BigDumbDinosaur

gravatar


How many miles are on the car?



Wed Jul 11 17:45:42 2012: 11195   TonyLawrence

gravatar


105,000 and change as of today..



Thu Jul 12 17:50:13 2012: 11198   BigDumbDinosaur

gravatar


105,000 and change as of today

A two to three MPG loss really shouldn't occur in 105,000 miles under normal circumstances. Your car might benefit from replacement of the fuel injectors. I replaced them in my 1994 T'bird at 150,000 miles and saw both an improvement in performance and fuel economy. Something to look into. Also, have you had the timing belt replaced?



Thu Jul 12 17:53:58 2012: 11199   TonyLawrence

gravatar


Yes, timing belt and injectors were replaced a while back.. all under warranty, which was nice..

It could be that we do far less highway driving now..

------------------------
Kerio Samepage


Have you tried Searching this site?

Unix/Linux/Mac OS X support by phone, email or on-site: Support Rates

This is a Unix/Linux resource website. It contains technical articles about Unix, Linux and general computing related subjects, opinion, news, help files, how-to's, tutorials and more.

Contact us





If debugging is the process of removing bugs, then programming must be the process of putting them in. (Edsger W. Dijkstra)

The danger of computers becoming like humans is not as great as the danger of humans becoming like computers. (Konrad Zuse)












This post tagged: