Picture of Save Gas!  Change the way you drive.
What better way to be eco friendly than to change your gas mileage? Seriously think about it. The less gas you use the less our mother earth has to be drilled, poked, and prodded for that precious black sludge.

Petroleum accounts for 40% of the worlds' energy consumption... OUCH

This instructable will show you various techniques you can use DAILY to reduce your gasoline or diesel consumption.

Contrary to popular belief the aftermarket products that claim to save you gas mileage actually do nothing. Sometimes they can even have a negative effect.

Before we begin I would like to state that I am an automotive technician. I have to test drive vehicles on a daily basis. By implementing these techniques you can improve your gas mileage. Getting reprimanded for consuming too much of a customers gas is not fun! So lets get started.

Step 1: Products to stay away from!

Picture of Products to stay away from!
Lets start with a few products out there that you should stay away from. I'll stick with the main three.

ALL of these products have been proven to be ineffective.

1. Magnetic Ionic Save. A magnet clipped to the fuel line to reduce CO emissions.
Here at the shop we have a 5 gas analyzer and I had some spare change. I decided to test this product on my down time.
Tests showed that there was no change in CO emissions when this product was installed.
Fuel consumption was measured in ML over a 2 minute period at 2000 RPM. Once again NO CHANGE.

2. Torpedo type intake devices. These devices are simply tin or steel and claim to improve fuel combustion.
I would have personally tested this but on three different occasions we found them jammed in throttle bodies. NOT RECOMMENDED. High dollar fix for a low dollar product.

3. Gas Additives.
JUNK. Even the dealership that I worked at sold this stuff. I would refuse to put it in the tank. Clogs fuel filters and stays at the bottom of the tank.

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I have to lose weight? Not be aggressive when driving? and you want me to not rev the engine!?... Well ok if it helps I will work on my driving to save gas... (sniffle)

Ps I like the Idea of drafting behind a semi though.

i just wanted to know if it was actually possible to reuse the co2 after being filtered? for example, you take a compressor with you,a gas filter and a reuseable co2 tank . could you hook up your exaust pipe to your ompressor and refill your co2 tank?
fwater5 years ago
Step 5 states "your car consumes a lot of gas while it's idling". An automotive tech would know better. Idling consumes a tiny amount of gas. No automotive engineer would ever design an engine to be shut off and turned back on constantly in traffic, even if it was more than 30 seconds. Wear caused by rapid heat cycling can be high. Again, idling consumes very little gas.
gr33ko (author)  fwater5 years ago
Are you an automotive tech? Have you ever run a fuel volume test? Step 5 is completely true ESPECIALLY when the engine is still running cold. During cold engine startup (exhaust temps under 600 F) the O2 sensors are still in OPEN LOOP. This causes an excess dump of fuel because the ECU/ECM does not know how much fuel to add. It is simply "enough" fuel to start the vehicle. After the O2 sensors achieve CLOSED LOOP then it knows how much fuel to add. Before closed loop the fuel system is working purely off of a fuel map. By the way I am a technician with credentials to prove it.
fwater gr33ko5 years ago
Spare me the explainations, I know what open vs. closed loop is, I'm not going to take open loop running into account because no matter what you do, that's what happens at cold start. After the engine has gone into closed loop, does an idleing engine consume a large amount of gas? If it does, cruising under load or accelerating consumes less? Are you an automotive tech? Have you ever been in a Turkish prison? I'm afraid that I will have to see those credentials. I got mine from the bottom of a box of cereal.
gr33ko (author)  fwater5 years ago
Idleing does consume a lot of gas if you allow it to idle for a while. That's what the point of the idleing statement was. Don't let it run if you're going to leave it a while. Here's my credentials.
gr33ko (author)  gr33ko5 years ago
fwater gr33ko5 years ago
Wow. Thank you for actually posting your credentials. Please don't be offended if I state that I was hardly serious about wanting proof. I can gather that you know a thing or two without photographic evidence. How hard would it be to find an accurate fuel consumption rate on a common car (10 years or less old, 100K miles or less, 4 cylinder) at idle? I would like to see some comparisons to consumption rates at medium throttle and cruise. Of course, now we've gone beyond the scope of a siple suggestion on a DIY website. You are knowledgeable and experienced, and though I disaggree, I concede. I'm taking my toys and going home. Yours too. I'm taking your toys.
gr33ko (author)  fwater5 years ago
For the sake of being nice I will tell you that most of the vehicles I have worked on were imports (85% roughly). If thats any consolation.
getting the fuel consumption rate is easy, get a ScanGaugeII. I use one in my 05 jeep liberty to monitor mileage and fuel consumption, when i start my engine while it's still hot the peak consumption during start up in never even double the idle consumption, and that's for only about 2 seconds of the start up, so if you're going to be sitting waiting for a train to pass, you might as well shut off the engine. Like a lot of these instructables say, changing the way you drive will make the biggest difference, according to the EPA testing, my jeep should get 17 mpg in the and 21 on the highway, and most people know those are usually a little on the high side. after changing the way i drive i routinely get 17 mpg in the city (my commute to work, i usually get to work about the time the engine is up to temp) and 24-26 on the highway that's a 14-20%(roughly) increase on the highway.
M150115 years ago
Cruise control set @ the speed limit & not driving aggresively are the best for efficiency based on my experience & remember "slower traffic keep right"
M150115 years ago
I've tried drafting several times @ 60-65 MPH on a route I drove on for a little over a 6 months before I tried drafting & have to admit drafting does work. I had some1 in the vehicle with me & they say they felt the a difference in the ride comfort between 30 feet & 50 feet.
I also tried a cold air intake & my rpm @ 65 MPH dropped by 200.
Because I deduct my gas consumption on my taxes I could tell.
All this took place over the span of 1 year 3 months.
I'll even give you the route.
Light traffic on highway 101 to 80 to 880 total 48 miles round trip.
Heater was the only thing running in the mornings to defrost the windshield.
Heavy traffic was a factor only about 10 days out of that whole time.
I know seems unbelievable if you know the area but thats my story.
Mileage went from 13 mpg to 16 average just by getting my cold air intake.
CameronSS6 years ago
I disagree in two places.

  • Since when does it take more gas to start a car? If it's running properly, it shouldn't take any more gas than an extra couple seconds of idling. On the other hand, most modern cars idle at 1500 rpm, which is way too fast and sucks gas.
  • One place that the cruise control will NOT save you gas is in hilly areas. The cruise does not have the ability to speed up while going downhill and let it slow down while going back up. Drive manually and pretend you're a semi in these areas.
Other than that, nice job!
who told you that cars idle at 1500 rpm. a normal automatic usually idles at around 700 rpm and manual at 500 rpm
Have you ever looked at a tachometer?
my truck does not have one
 my Yugo koral 45 alsodoesn't have tachometer
like Prometheus said it is only at 1500 for like a couple seconds right when you start it, and I am building truck number 2 from the ground up so I would kinda know where a car would idle.
I know it sounds off but do youre home work and read up on starting a gas engine. It's just like turning on an electric light or starting an electric motor or starting anything at all. The very most power you will use is at the start. Try pushing a car, the very most effort you will give will be at the START and on a flat ground once the car is rolling it will almost keep going. What this means is, and what is trying to be said is if you run into a store for 2 minutes you will eat less gas than if you shut off your car and strart it back up the same with a light and electric motor. Would you like me to hit the brakes every 2 feet as you push my car into the gas station and you have to get it rolling again?? Try it!!
gr33ko (author)  CameronSS6 years ago
Your car will consume more gas on colder starts. This is a proven fact. Even in warm weather initial starts. If the engine is not warm it the CPU is in open loop operation. When it warms up (600+ degrees F) it is in closed loop operation. Closed loop is when your CPU computes air fuel ratios. Open loop is a continuous dump of fuel. A predetermined amount to keep it running.


As for the cruise control you are right. Hilly areas will not improve gas mileage. That is why I said "typically".
To clarify for the rest of you: "open loop" is the ECM's )computer's) "default" values for engine operation. In Open-loop-operation, the engine is cold and the ECM simply maintains engine operation and disregards prior driving habits. When an engine is cold, it does not operate at peak efficiency. People have a habit of getting the car into motion before the starter-motor has come to a complete-stop due to a complete lack of respect for technology and a sense of entitlement to instant-gratification, so this mode is a precisely-tuned set of values to maintain a base-level of driveability while the engine is still cold. The oxygen-sensor is not capable of operation in this mode, so it's input is useless. "Closed-Loop" operation is when the engine is warmed to operating temperature, and the oxygen-sensor is within an operating temperature as well. At this point, "block-learn" is employed to maximize efficiency due to previously-recorded driving habits over the past 20-50 or so starts that have achieved a "closed-loop status". This is yet another reason why short-trip-driving can destroy a car in less than 150k miles, partly because the computer never learns anything about the driver. Gr33ko, well-intentioned project, despite missing a few details. You know your game sufficiently, and i can certify that as an ex-racer and lifetime automotive-engineer, you are making a useful effort to teach those who learned less than they should have in Driver's-Ed...I dispute any use of cruise-control as a means to save gas, but you may have a point as some people drive so badly that it can be a necessity.
gr33ko (author)  Prometheus6 years ago
Once again thank you!~
By typically I mean pretty much all the time.

May want to rephrase that, then.
gr33ko (author)  CameronSS6 years ago
Done and done! :)
By default, 1500 rpm is not "way too fast" for a cold-start on a low-displacement engine. The reason the idle speed is so high initially is to do the following: 1) Peak the oil pressure to immediately lubricate the upper parts of the cylinder-head and maintain a minimal oil pressure while driving on a cold engine. 2) To speed the heating of the catalytic-converter and the exhaust manifold, to reduce carbon-fouling and to expedite an operational temperature. 3) De-foul the plugs and cylinder head as soon as possible for optimal reliability and to minimize abrasion due to carbon-fouling of a cold cylinder 4) Minimize stalling due to a cold engine being driven prematurely. 1500 RPM is often the first-stage of an open-loop cycle, then it drops to 1250, and then 1100, and then to closed-loop idle when the conditions of that mode have been met. This is not "way too high", these are values set in the ECM that are necessary for a predicted driving routine from the start. If you think a 1500rpm cold-idle sucks gas, imagine how bad your mileage is when you attempt to drive like normal on a cold engine. Idle really draws very little fuel by comparison to cold-engine driving. "Open-loop enrichment" is certainly much more than "closed-loop" operation, but at idle there is far less fuel burned to keep the engine running than used to drive on it. Those who drive automatics and are smart enough to know that a warm engine does better than a cold one, they warm up their cars by holding the brake as they idle in "D" or "R", because the engine is loaded and the transmission will warm the engine as well simply by being in "gear"... BTW, "kick-up" for automatics when placed into a driving gear is 1800rpm when cold and at no-load, when the wheels are off the ground.....just so you know....warm "kick-up" is about 1400 rpm no-load.
gr33ko (author)  Prometheus6 years ago
Good info Prometheus! Thanks~!
RickO55 years ago
One note on fuel additives: A fuel additive that I imagine wouldl boost gas mileage in certain cars? Octane booster. Assuming you're in a car that will operate differently using different types of gas (some Mercedes, Nissans, and Cadillac will to name a few) the car will change its valve timing and ignition timing, as well as amount of fuel injected and in some cases boost pressure in relation to type of gas you have. If will optimize up until it sense "knock", at which time it will dial back. Now, Im not sure how octane boosters effect the rest of your engine, Ive never used them myself. Just something to consider.
gr33ko (author)  RickO55 years ago
If your car requires 89 octane thats all that you should use. Higher octane is purely detonation protection.
RickO5 gr33ko5 years ago
Usually. If you have a car that adjusts itself to make use of the extra compression it can safely achieve without knocking, higher octane gas could help, I dont know for sure, Ive just seen in some cars manuals that it is advertised to.

It makes sense though, higher compression = higher efficiency. Higher octane = higher possible efficiency.

But yeah, I put 87 octane in mine, regardless.
fwater5 years ago
"Aggressive driving reduces your gas mileage by 33% highway and 5% in town!" Where on Earth are you coming up with those numbers? "Tune er' up!" Modern spark plugs usually last up to and often in excess of 100,000 miles. Exception- when the engine is short shifted in an attempt to save mileage (doesn't work, low volumetric efficiency at low RPM vs medium RPM), plugs will last magnatudes less time. It's not just the author, but people all over are falling for this feelgood nonsense. These suggestions and thier accompanying statistics are pulled out of thin air. Pardon my tone, but they are repaeted all over the internet and the news without question. Lose weight from the car, stay out of the thottle. Done.
gr33ko (author)  fwater5 years ago
"Lose weight from the car, stay out of the thottle" So you agree? With the staying off of the throttle?
fwater gr33ko5 years ago
I do.
fwater5 years ago
The drafting effect occurs at speeds in excess of 80 miles an hour with cars, and requires distances between vehicles of less than 3 feet. The effect behind a semi is chaotic high an low pressure turbulence, making for a fun jostle, but no draft effect. The benefit is not significant, but in fact none at all. Lightenning a car is, however, an effective way to increase mileage, not just slightly noticeable as the author states. Removing random items from the trunk may be only a slight improvement, but how about removing the spare and jack? Unsprung weight (rims, brake discs) offer good benefits as well. Take cues from the race crowd.
RickO5 fwater5 years ago
Very false. Drafting -can-, depending on your vehicles design the vehicle you are following, make a huge different. Aerodynamic drag becomes a significant factor at more that about ~45mph, also depending on the car. Depending on the vehicles involved, the drafting effect may be enough to pull your car along without the use of you engine. On a couple of occasions Ive managed this for a few miles, both were ~10 feet behind large tractor trailers, on level to slight downhill grade, at speeds of about 55mph. On the other hand, the jostle you mention can be dangerous. It can your vehicle less stable, and its a sign that your vehicle is in an area of turbulence unlikely to produce a drafting effect. Take cues from the race crowd? They all draft.
RickO5 RickO55 years ago
Straight off wikipedia: "For example, hypermilers using this technique can achieve 75 mpg or more. Some sources say that the most common tailgating does not save gasoline even at freeway speeds because one is likely to accelerate and brake so frequently that any aerodynamic savings are lost through the brakes. On the show Mythbusters, drafting behind an 18-wheeler truck was tested and results showed that traveling 100 feet (30 m) behind the truck increased overall mpg efficiency by 11%. Traveling 10 feet (3.0 m) behind the truck produced a 39% gain in efficiency."
fwater RickO55 years ago
Please pardon my skepticism regarding wikipedia. A matter of opinion now, I suppose. We don't aggree on what are facts or possible facts. On my part, I will aggree to disaggree.
CaptInsane6 years ago
I'm not sure if this is nation-wide or not, but in some places it's illegal to draft
i love the pictures
zwei26 years ago
how about 42 mpg? does anyone ride a stock car that does something like that? I'm doing this on my day average.
JacobAziza6 years ago
Step 6 is mistaken. This is a very common myth. This used to be true for large engines with carburetors. Computer controlled, fuel injected, and smaller engines use very little extra fuel to start. If you are going to be stopped for 30 seconds or more (depending on the vehicle) it is better to shut it than to idle
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