Instructables

The Comprehensive Guide To Saving Money on Gas

Tired of paying out the nose for gasoline? We all are, and while most of us can't give up our cars entirely, and there are things we can do to ease the pain.

The popular option to consider is getting new transportation entirely. Both diesel cars and hybrids can get over 50 miles per gallon, which can add up to major money savings. I wouldn't recommend buying them unless you are already planning on buying a replacement automobile, as the cost will take a while to be offset by gas savings. Likewise, purchasing a motor scooter for short trips can save a lot of money if you make enough use of them. These scooters can get over 100 miles to the gallon, and are a blast to drive, so crunch some numbers using this calculator this calculator

The best options of course are to make better use of public transportation, walking and biking, but for many of us, these options don't fit well into our lives. With this in mind, I've assembled a list of tips and tricks will help keep as much green in your wallet as possible while still staying mobile.

If you like this article, please check out my website at http://www.rickywillems.com
 
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Joenavy854 years ago
it took a round trip from Chicago, Illinois to Canton, Ohio to get my wife to believe this one. She drives a Honda Civic Si and it says PREMIUM FUEL ONLY on the door for the gas cap. i told her to fill up with premium for the trip there and then run the tank almost empty while there and then only use regular on the way back. She took my ScanGaugeII and got 31.7 MPG  on the way there and 30.9 MPG on the way back. And for all we know that variation could have been caused by wind. Either way that .8 MPG increase isn't worth the extra 20-25 cents a gallon.
That's really not a valid check due to altitude changes, wind speeds, ect, different brands/mixes, ect. Chicago is one of the cities that uses its own boutique fuel blend, which your Civic may not have liked.

A valid check would be a 5 tank average under what is your normal driving conditions. Run 87 for 5 tanks, then run 93 for 5 tanks, and see what the average is. When comparing things like this, keep as much the same as possible.
Thanks for the live data, I had often wondered about this. Does fuel choice affect warranty on cars specifying premium fuel?
fwater4 years ago
"50% throttle at 1200 rpm's uses less gas than 10% throttle at 2500 rpm's" Another in an endless line of impossible statistics. Where are the numbers from? They do look impressive and make a person feel good, though. "The engine is more efficient when it does not have to pump air past a closed throttle." An engine does not pump air past a throttle, it sucks air past it. It has no impact on efficiency. Cam profile, injector pulse width, throttle position, and engine RPM dictate efficiency. A Honda Civic I used to own turned 2250 RPMs at 55 to 60 MPH. Honda engineers probably had a reason to have the car in that powerband at highway speeds. I have commented on other Instructables on increased gas mileage, and I will again say please pardon my intolerant tone, but efficiency vs. RPM varies from car to car, and oversimplifying it is misleading. Unsubstantiated statistics and numbers imply that whoever states them knows what they're talking about, further confusing the mileage issue. Lighten the car, easy on the gas pedal.
Make a database on your PC and implement date, mileage, fuel quantity you read on display and calculated on price end expence , fuel price, air filter and oil changes, tire pressure checkings, whatever you consider important and in a few months you'll see what really happens with your car. I do that since 2005, quite boring but you'll find out many actual facts on this subject.
RickO5 (author)  fwater4 years ago
I would argue pumping air past a restriction is effectively the same as sucking it through. That being said, after looking into it further, this only makes a difference at near the engines limits, so it probably isn't relevant. Its the same argument as clean vs dirty air filters actually. And, you did actually catch another mistake for me, I meant to make it clear that the 1200 vs 2500 was specificly the results for a vehicle I own. You're absolutely right about honda engineers having a reason the engine maintains that speed, and that every car is different. Thats the whole point of this page of the article. In your case, the "sweet spot" that Im recommending you try to stay around or below would be 2250. What I found is that engineers usually design their cars to be most efficient at highway speeds (no surprise), and that by operating your engine at a similar rpm as you would on the highway, mileage can increase.
RickO5 (author)  RickO54 years ago
Also, for a little more lovely math.

Im just pulling off a generic Toyota fuel map. (back calculated volumetric efficiency based on MAP readings, engine load, throttle position, ect)

VE at 1000rpm, 50% throttle = 71%
VE at 2500rpm, 10% throttle= 54%

to find the relative amount of fuel being injected (assuming all other factors equal), simply multiply rpm by VE.

710 at 1000rpm 50% throttle, 1350 at 2500rpm, 10% throttle.

710/1350=~53%,

meaning 1000rpm 50% throttle uses around half as much gas as 2500rpm at 10% throttle.

This is assuming certain other variables are constant, which is likely not the case, so this figure is an estimated example only.
fwater RickO54 years ago
Your work to support your claims surprises me. It's no secret that the tone in my citicisms was very dismissive. We now fing that you are not simply shooting from the hip, but instead have made very informed statements about mileage. Good job.
RickO5 (author)  fwater4 years ago
You were quite right to criticize, I provided none of the reasoning or math for my suggestions in the article, and with the unfounded claims that get thrown around on the internet, I should lend credence to myself and show my work. To an extent, it's still shooting from the hip, I cant say these figures are always true for every car, but they are tips and guidelines, not a scientific paper full of hard-fast rules. My inclination was that the reasoning and math would be beyond the scope of the article, and beyond what most people would care to read, but perhaps the average instructable reader wants a bit more.
arionisa5 years ago
Any car buil in the last 20 years or so has a sealed fuel system, parking in the hot sun or in the shade makes no difference at all since any fuel vapors caused from evaporation are captured inside the sealed system and will return to a liquid state once they cool down. In fact, newer vehicles ("96 and up) generally have a sensor built into them so that if you don't tighten your fuel cap all the way (to capture the vapors), your check engine light comes on. A good idea if you drive an older car I guess, but useless for anything "recent".
That's true, there are two pipes from the fuel tank, one comes from the fuel pump inside the tank, the other takes fuel back from engine to the fuel tank. Consider that the fuel pump cools and so endures more it's working life if submerged by fuel. That means more or less something like two gallons fuel in your tankat least. Remember it does exist a fuel filter too between the fuel pump end the engine, better to clean , possible in some diesel engine, or change. It surely helps pump life too and I can tell gas pump failure is a real bad nightmare, I changhed mine in a parking lot, a most difficult task I ever tried . Gas filter in my car was almost filled of an unclassified black dirt after 50.000 miles when I changed it .
Clean new engine air filter and a well checked tire pressure are mandatory as it results in my personal mileage, fuel, oil and filter changes database. Keep a hand or pedal air pump in your trunk it may help or even save a lot.
so why do new cars have a fresh air tube on them?? If the system is sealed and you pump all the gas out of the tank you'll have a vacuum in the tank and won't be able to get the cap off to refill it.
delias12 years ago
im having a hard time figuring out where you are getting your data from
RickO5 (author)  delias12 years ago
Depends on which data you mean. A lot of it is personal data collection using the vehicles I have access to and an OBDII laptop connection and log tool. Other parts are government sources, as well as other sources.
delias1 RickO52 years ago
i guess it would be the one on your speed reflecting fuel mileage, i know you lose fuel economy the faster you go but 3 mpg per 5 mph? that seems a little drastic to me. i drive a 2005 f150 with a 5.4l, at 110 kmph (i live in the great white north) i pull 21 mpg over a distance of 450 kilometers and use roughly half a tank, now at 145 kmph i get slightly less then that, i think the last i checked it was roughly 19 mpg. sorry i have no idea where i was going with this, i sorta lost my train of thought half way through.
Good hints!. Still, a very important one has been missed (i guess): get a low mpg car. Imported Europeans are the best/more common on fuel saving.

For instance, I have a little Citroen (diesel, 5 seats, 1992) in which I ride every day to university. Most is country roads, but include some city traffic and a few pedal-to-the-metal moments. I never went below 52 mpg (us gallons). Back in the 90s, an advertised announced a best of 64 mpg for this car. It held a record for economy until 2008, lost for a Peugeot HDI)

Cars that go below 25mpg are quite rare in Europe. They're either big luxury cars, US cars, or pre80's. Maybe because we rely on small blocks, I don't know....
Metalhead913 years ago
if your going down a hill, throwing your car into neutral is actually detrimental to you fuel economy. Most new cars (2001 and up) are fuel injected, and when coasting down a hill in neutral, your car uses x- amount of gas to keep the engine idling. If your car is in gear going down a hill, the injectors will supply the engine with less amount of fuel than it would while idling. think of it this way...if your coasting down a hill under no acceleration from fuel, then the tires are spinning the engine, so why should the gas have to?
RickO5 (author)  Metalhead913 years ago
I also meant to add, keeping your car in gear also slows your car down depending on your speed, gearing, incline, ect. This might be fine, but it might also be a waste of potential energy you could be using to speed your car up. Cruising a little faster down hill means having a little more momentum to go up the next. (staying within safe speed limits of course)
RickO5 (author)  Metalhead913 years ago
This is true on some fuel injected cars, but not others. For example, I tested this in a 2009 Mini-Cooper about a week ago. According to it's ECU hooked to my ODBII reader, it used several times as much gas when decelerating in-gear than it did when out of gear, depending on the engine RPM. I've tried it on other cars as well, with abut 50/50 results.

Hmff4 years ago
That was an ok way to save on gass but we need more modifcasons than driveing habits.
Joenavy85 Hmff4 years ago
the problem is there are only so many mods that will help, I'll be doing an instructable later this summer on mods I'm doing to my jeep. I currently get around 26 MPG on the highway in my '05 Jeep Liberty and the EPA tested it at 21 MPG on the Highway (an almost 20% increase). And that was mostly from changing my driving habits.
gizmosass5 years ago
Anyone remember when the national speed limit was 55mph? Seems to me I recall it had something to do with energy conservation. Well, flash forward to today. I have been advised by a very experienced mechanical engineer to slow down to that speed on the highway to get optimal gas mileage. Today I tried it. My gas mileage on my late model Jeep Cherokee while running 75-80mph on the interstate is a very disappointing 19.5. When I slow down to 55mph on the return trip today, it went up to 27.1. And driving more slowly decreased my stress. I noticed a lot of other drivers have slowed down, presumably since gas has increased to the current prices. I'm thinking that perhaps there would be less stress on the roads, and perhaps less deadly accidents, if we all slowed down. I know I'll be happily over in the right lane poking along from now on.
Wait, FSJ Cherokee, xj cherokee, or liberty (Only a cherokee in non US regions)? For the first two: HOLY CRAP! Nice dude! For the last, isn't it rated for 27 stock?
i know this is a little late. i have an '05 Liberty and get around 26 on the highway, it's rated 17 city/21 highway, that's almost a 20% increase. i have also tweaked  it a little bit(the car not the engine), but before those changes i was getting around 24 about a 14% increase.
RickO5 (author)  gizmosass5 years ago
Thats absolutely true. Most cars are designed to be the most efficient at 55 mph. Some a little less, some a little more. (My car seems to do the best at 50, our van seems to do the best at 65). Everyone should try to figure where there peak mileage is, and be there as much as possible. For many, that just means slowing down a little :)
your nighttime fill up maths is wrong... 1.16% of $80 is $0.928 so you still save a buck, but certainly not $10 :)
RickO5 (author)  TheScientist5 years ago
Oh lord, thanks a lot. ill fix that straight away.
hehe no worries :) i think your point is still valid, especially for people who use a lot of fuel... a couple of bucks a week adds up over the years!
But if you look at the pump next time you fill up, you'll see the sticker says the amounts are temperature adjusted (at least the pumps in Ontario Canada are).
One station I use (Costco) does not temperature compensate, most of the others do.

You can always ask the attendant what the tank temp is, it is in a report they generate every time the tank is filled.

The tank temperature will change little over the course of a month, except when it is filled. In the winter, fuel after a fresh delivery, in the summer, fuel before. (If you know the patterns.)

The number 1 fuel economy fix I have found is to get a real time fuel economy meter. (Scangauge for newer cars, MPGuino for older fuel injected types.) You can instantly see what works and what doesn't.
RickO5 (author)  Mister_Caipirinha5 years ago
Its not temperature adjusted in Maryland where I live, but thats good to know.
RickO5 (author)  RickO54 years ago
Correction: Pumps are now temperature adjusted.
fwater4 years ago
"Driving around looking for a better spot...uses a ton of gas" A ton. Wow. How about very, very little. You're driving me nuts! "Keeping your tires properly inflated, your oil changed, your transmission serviced..." OK, good. Sound advice. "...your air filter clean, fuel injectors cleaned..." Oh no, you were so close to getting through a whole step without repeating a falsehood! An air filter would have to be literally blocked off to have an effect on mileage. Why? As a filter becomes more restrictive, the engine knows nothing more than the total flow though the MAS, flowing the right amount of gas for engine RPM, load, throttle position, etc. Less flow through the filter causes you to push the gas pedal further, sucking more air, but having no effect on the engine managements system's calculations, again all based on flow through the MAS. "Any one of those factors if left out of check can hurt mileage by 10% or more." Another statistic pulled out of tin air. I'm sure you believe it, but whoever came up with it has an agenda.
RickO5 (author)  fwater4 years ago
Wow, just picking apart the article... Okay. Uses a ton of gas: Define a ton? To me, if driving around the parking lot for 5 minutes uses enough gas to get you a couple miles down the road, you're using a ton of gas. Moving around a parking lot, at least in my experience, is nothing but speeding up a little, then almost immediately slowing down, repeated over and over again. As for fuel injectors, you're suggesting a clogged fuel injector will produce the same fuel atomization, power out, and combustion efficiency as a new one? Does that make any sense to you? And as far as air filters go, I can't really do anything but flat out disagree with you there. You are correct, the ecu will maintain proper air fuel mixture, but thats not the point. A dirty air filter does make a sizable difference in economy. I might give you some slack here, if I hadn't physically observed lower fuel consumption rates on vehicles after an air filter change. Guess what that observed change was on the 2nd to last vehicle air filter I changed? Thats right, 10%. I can see why you'd say you say that, seeing as though youre backed by the government fuel economy website. (They do admit that carbureted engines show a difference, but in their cited article they did not measure differences in FI cars) If you havent already, take a look at the article. You clearly have a good eye for picking out problems, you'll find plenty in that one.
fwater RickO54 years ago
I do have a good eye for picking out problems, to the point that I come accross as arrogant or argumentative, this being a prime example. Not my intention; I have simply seen too many unsubstantiated claims. You have shown that you are magnetudes past the average "I read somewhere" guy. I myself have never observed a significant increase from an air filter change. My observations could be affected by- air filters may have not needed replacing, the cars were high performance and had filters with perhaps 100% more surface area than required, or any number of variables logging MPG before and after the filter change. As for the fuel injectors, atomization and pattern will affect power output, but an injector simply running at lower capacity due to a restriction will be corrected by the ECU with a longer pulse width or duty cycle, depending on the system. Let's call it a draw. With the edge to you. Just a slight edge.
RickO5 (author)  fwater4 years ago
Lower output capacity isn't a particularly a concern. If you ever have the occasion to use a fuel injector outside of a car, try using one that's fouled. A normal injector puts out a nice, even spray. A plugged injector does the same, only with fewer jets of mist. A fouled injector (Im making up this term, Im assuming injectors in this state either have a carbon film on them, or the individual ports are partially plugged) will spray in odd ways. One of the ports might spray a straight, non-misting stream, one might be spraying at an extreme angle, one might be spraying intermittently. I only comment again to say its interesting to see injectors that arent "plugged". Plugged injectors probably dont cause as much of a problem. Id also imagine (guessing) that fouled injectors would be easier to clean, as the solvents can penetrate the individual orifices more easily. Also i should concede Im probably misinterpreting some of my past experiences. Previous to the last air filter change I did (which was just an air filter), I replaced an entire intake system on my brothers car. He's averaged about 3 miles per gallon more (~15% increase) and Ive been attributing that to the air filter, though it could just as easily, and probably more likely be the temperature of the air, which is now coming from a different place in the engine bay.
fwater RickO54 years ago
Yep, changing more than one component can muddy up what really works and really doesn't. Drag racing thing, change one thing at a time when going for that last ounce of performance. Sweeping changes (intake manifold, headers, exhaust) are less important to quantify individually. I would expect a contribution to mileage and power be made by both the filter and cold-air intake in your situatuion. Who knows what contributed to what and how much. I have seen a fuel injector operate in free space when installing a water injection system on my Grand National. It was, of course, unfouled, so I cannot comment. But it looked neat.
fwater4 years ago
It continues... pure nonsense, but backed up by math, so it must be true, right? The temperature past just a few inches underground fluctuates very little. By your thinking, we in MN must be saving an absolute fortune in January. The problem here is, you put this myth right after a suggestion to look up cheaper gas prices. This is an undisputable and valuable way to save a buck in the car. Most people won't look at the two different topics and dispute this one because the don't belive the one about the weight of gas, they will instead believe what you say about the effects on gas at noon because the first suggestion is a truth. Please, hypermilers, environmentalist crusaders, modern-day hippies, stop with the unsubstantiated claims.
RickO5 (author)  fwater4 years ago
I had no idea I was subconsciously organizing my tips to toy with the minds the readers! And by that, I mean the order was entirely random. Actually, this is a claim I have been meaning to take off of here, but not for that reason. Modern gas stations that most of us fill up at (and that most states require) have temperature corrected flow rates. I was basing this on the only gasoline pump Ive had the pleasure of disassembling, that was made sometime in the 40's. Either way, thanks for the comment.
fwater RickO54 years ago
An easly repeated mistake. We all have seen something or another repeated endlessly accross the web, and this was one. But, gone forever now! Perhaps the new number 11 could have something to do with the importance of a properly-functioning emmissions system. Dozens of different parts, each able to cause lost mileage when clogged/broken/even missing.
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