Fuel Economy Tip – Follow the “3 Second Rule”

Here’s a tip that will not only help you increase your vehicle’s fuel economy, but will also help you become a much safer driver:

Follow the “3 Second Rule”

As you are driving down the road – particularly at highway speeds – make sure that you give keep plenty of space between your car, truck, SUV, etc. and the vehicle in front of you. In most cases, you are giving proper spacing if you are traveling three seconds behind the car in front of you, however, you will likely need to give more time and space if you’re driving in bad weather.

For those of you who don’t know how to tell how close you are traveling to the car in front of you, pick a set object up a head – an exit sign, a light pole, etc. – and once the bumper of the car you’re following crosses the designated object, begin counting and don’t stop until the hood of your car passes the same object.

Following the “3 Second Rule” will help keep you from constantly tapping your brakes and accelerator every time the car in front of you slows down and speeds up. By avoiding tap dancing on your brake and accelerator pedals, you can significantly increase your fuel economy. Here’s why:

By tapping your brakes, you essentially waste the energy it took to get up to and maintain the speed at which you were traveling. Then, In order to get back up to your previous speed, you’ll need to hit your accelerator, which, obviously, will take some energy. This energy – both the wasted energy and the newly required energy – came from or will come from the burning of your car’s fuel.

If you leave plenty of space between you and other drivers, you’ll give yourself time to adequately judge whether you actually need to use your brakes, or if you can just ease off the accelerator and coast for a short while. If you coast, you’ll still lose some of the initial energy and will still have to use fuel to get back up to the previous speed, but it won’t be nearly as much as if you had used your brakes.

Using less fuel tends to mean better gas mileage!

And, in terms of safety, by having plenty of space between you and the car ahead of you, you’re much more likely to avoid a serious accident because you’ve given yourself enough time to either come to a stop, or make the proper “evasive maneuver.”

Comments

  1. One wonders if this rule would be offset by slip-streaming/drafting?

    ie: done properly with little breaking you could probably get even better mileage. The 1 second rule?

    http://en.wikipedia.org/wiki/Prop_wash#Slipstreaming.2FDrafting

  2. You also lower your chance of rear ending the car in front of you, saving you money in increased insurance premiums and repair headaches.

  3. Ummm… I just read a profile of a hyper-miler in Esquire who “drafts” (read: tailgates) to improve mileage – that runs counter to the “3 Second Rule” you’re referencing here. Also, if you ease off the gas and go from 55 to 45 or if you brake and go from 55 to 45 – either way, you will use the same amount of fuel to get from 45 back up to 55. Last, your statement that “Using less fuel tends to mean better gas mileage” almost made me spit-take my coffee. “Tends to?” It does absolutely. Use less, equals saves more equals better mileage.

  4. Anyone with half a brain already knows this and probably drives reasonably instead of like a retard.

    The rest of the general public will probably never listen.

    I suppose it’s worth a shot. >_>

  5. WIsh every driver followed this rule!

  6. If you pull this crap during rush hour I will tail gate your ass until you move.

  7. Actually that’s incorrect. Driving close to the car in front of you creates a drafting effect that saves more gas than the little bits of braking you might do.

  8. wow you would think a blog dedicated to fuel economy could come up with better than this

  9. Adam, that’s just plain dangerous. I hope you’re carrying a solid insurance policy and you’ve had your brakes checked recently.

  10. I understand the basics of drafting, and yes, if it is done properly it will increase your gas mileage.

    Unfortunately, in order to get a significant gain while tailgating other passenger vehicles, you have to get extremely close to the other car’s bumper. I know with semis, there’s a greater distance just due to the size of what you’re following.

    Either way, is it really worth the risk to get a mile or two extra per gallon? Probably not.

  11. Drafting in dense traffic is Darwin’s way of making asshats into meatpie.

  12. always draft behind semi trucks, your car will always brake faster than a semi, even if your driving a hummer. so if you do rear end the semi, it probably rear ended another car. and you can claim that it was the trucks fault. haha

  13. >if you ease off the gas and go from 55 to 45 or if you brake and go from 55 to 45 – either way, you will use the same amount of fuel to get from 45 back up to 55

    Yes, but you’ll cover less distance when braking to 45 than coasting to 45 and that of course reduces mpg.

  14. Its ass-hats like you I tailgate as hard as i can during rush hour

  15. 8086Chiled says

    This is all fine and good but please for the love of all thats holy DRIVE THE SPEED LIMIT while on the freeway. If you are too timid to maintain traffic speed stay in the right lane. Everyone should stay out of the left lane unless they are actively passing.

  16. Save even more gas: get right except for passing; just because you think 50 on a 55 is perfect doesn’t mean everyone else agrees.

  17. Please don’t mention drafting ever again. Ever. Unless you are driving a track car with commensurate experience and skill, drafting is outrageously stupid. We’re not talking about a one second lead for drafting. No at sixty it’s more like a 150 ms lead. Guess who doesn’t have those reaction times, tires, brakes, and suspension components? Don’t kill someone else because you failed high school physics and junior high algebra.

    And while I’m at it, you will save gas by coasting rather than braking. That is if you have a manual transmission which you do if you’re worried about gas mileage. When you coast with a manual in gear, the wheels actually help turn the engine. Not to mention, you save money on brakes.

  18. I’m with Trent on this one. “If you pull this crap during rush hour I will tail gate your ass until you move.” Your gonna have a tough time readjusting your 3 seconds when you have cars coming from all lanes pulling in front of you because you want to give yourself some cushion.

  19. I don’t agree. In city traffic, demand lights require that you stay unsafely closer to the vehicle in front of you so that the traffic signal doesn’t change, allowing you to stay in motion and save gas. If you follow the 3 second rule the traffic signal will most certainly change during peak traffic hours, forcing you to come to a complete stop. Personally, I think demand traffic lights are idiotic because they encourage motorists to disregard many traffic rules there by making the congested road system even more dangerous. If we want to save gas, contanct your congress representative and inform them that you would prefer synchorized traffic signals in and around city centers; which would save the average driver 10% in fuel cost and lower the Nation’s crude oil use/production/consumption respectively.

  20. 0oo Following distance vs. drafting oo0

    Drafting is an effective technique only when you are following a vehicle which is not aerodynamically sound (read semi truck). You can feel when you’re drafting. Get close behind a boxed 18-wheeler (about 100 feet or about 1 second behind), roll down your window and stick your hand out the window. It will feel like you’re traveling 25 mph.

    Drafting regular commuter vehicles is inefficient and unsafe and is not called drafting. It’s called “tailgating”. You will save more gas by traveling at a constant rate than you will by tailgating someone who speeds to a jam in the road, forcing you to slow down as well.

    Also, drafting is inefficient at non-highway speeds and you can ride my arse all day if you want, but don’t get pissed off if I’m not racing to the red light. I’ll drive 15 mph if I have to in order to hit the green. And it pissed me off when you cut around me and force me to stop, because you’re blocking the space I was going to cruise passed stopped traffic.

    And I also have no sympathy for your anger at me for driving posted speed limits. Read the signs. If you don’t like the laws, petition for change.

    Our leaders will not be held responsible until you hold yourself responsible.

  21. Generally, this is a good tip – another way to say it is “anticipate conditions ahead of you” or “pretend you’re driving with a hot cup of coffee between your legs.”

    In other words, for you to maintain a steady speed (generally best for efficiency ignoring “pulse and glide” techniques which are also relatively steady) you need to anticipate the driver in front of you braking then accelerating … leaving a buffer allows a more constant and efficient speed for you (and the people behind you actually).

    In traffic the same rule applies. This will mean you’ll be cut off from time to time, but don’t let it get to you and remember than you’re more relaxed driving is faster in the end for you and those behind and beside you.

    @BoredQuiz – couldn’t agree more, but I guess the point is to roll out the tips daily so get people interested and then to read the collection of tips as a whole or look to ecomodder.com’s list of 100 tips (which is generally very good).

    @Trent – you’re tailgating will only cost you more gas and potentially a ticket or damage to your car. The person ahead of you who is driving with a gap between cars does not slow you down at all (well, maybe 1-2 seconds over the course of your trip) and may actually speed you up because they won’t need to slowly accelerate after braking but will already be at a higher speed when the traffic does finally break.

    In sum, drafting saves you very little gas over short periods and saves none (or costs you efficiency) if the driver ahead of you is not driving at a steady pace. A buffer space is more likely to save you some gas and certain to make you more relaxed and save you many worries and accidents.

    Excellent collections of efficiency tips:

    http://howto.wired.com/wiki/Get_More_Than_40_Miles_Per_Gallon_Without_a_Hybrid

    http://ecomodder.com/forum/EM-hypermiling-driving-tips-ecodriving.php

    http://www.cleanmpg.com/forums/index.php

  22. I wouldn’t move because, despite what you think, i don’t care if you get where your going 3 10ths of a second sooner or not.

  23. @amused. The “real” rule is something like a roughly 1 second following distance for each 10 mph you travel.

    Thus, your following distance is dynamic and adjust to city and highway speeds.

    Also, depending on your state, you can look at specific following laws. Here in NV, the laws is very loose; “The driver of a vehicle shall not follow another vehicle more closely than is reasonable and prudent…”. You could probably get away with drafting in most cases here in NV.

    Also, for highway driving, I’d like to point out how much more efficient it is for the whole of traffic for you to stay right, except to pass. The left lane shouldn’t be though of as the “fast lane” but rather the “passing lane”. Once you’re done passing, get the heck out of the left lane.

    And I’m sick of people claiming that they’re aware of their environment and they wait until someone gets behind them. When I ride in the car with these same people, I see them being angrily passed on the right.

    I don’t care if you’re going 80mph. Someone else is going to want to go 90.

    Happy Driving!

    =)

  24. don’t want to get tailgated? stay the fuck out of the passing lane. (that’s the one on the left)

  25. I hope you drive near Vancouver BC some day so I can tailgate the hell out of you, or pass you while drafting behind a car in the fast lane, as I assume the high speed of the fast lane also scares you.

  26. If you drove the same speed as me and not half deaf and blind seniors I wouldn’t have to tailgate you. As for fuel efficiency….I drive a corolla it doesn’t matter how i drive it.

  27. Doug McFall says

    OK safety issues aside, while you’re “drafting” behind my truck, I can’t see you. So I can’t let you by me when I see the lane is clear ahead (from my vantage point six feet or so higher than you). I know nothing I will say will get you to listen, but ask any professional driver what they have seen the results of following too closely to be sometime. I hope you have a spare hour and a strong stomach when you do, because it’s real ugly and it’s everywhere.

  28. Feel free to tailgate then, to the people that state that they will tailgate the hell out of someone.

    I have a simple rule – If I cant see your headlights and you drive a car, you are FAR too close to me. I slow down. The longer you tailgate, the more I slow down. I will continue to slow down until you pass me – which is all I want you to do. Get the hell off of my ass.

    I have been on the highway doing 40 because the person behind me has to be such an asshat, guess what so can I.

    I typically drive 5 over the limit which is the most I can do without risking a ticket. I usually see two people pulled over on the way to and from work, and I would really prefer to avoid another speeding ticket.

  29. betterdriverthanyou says

    Well, if you drive fast enough then it wouldn’t be a problem. The burden shouldn’t be the one in the rear, but the one ahead. If the person behind you is driving too close, that means you are driving too damn slow! MOVE OUT OF THE WAY!

    I drive the 405 freeway in LA everyday, and everyday there are people who do not go with the flow of traffic, thus causing congestion. The only way they get the hint to move out of the way is if I get close enough to their rear to let them know they are moving too goddamn slow.

    The solution of this article sucks ass, it is counter productive. I can only assume the author of the article drives slow, drives without consideration of current traffic flow, or is barely intelligent enough to drive.

    Another point the author didn’t consider, in heavy traffic, if you leave a 3 second window, someone is going to fill that window. So, if you keep following the rule you are now 6 seconds behind the car you were originally behind. If I were an idiot and kept following this author’s advice, then I would move back 3 seconds, and again that window would be filled, now I am 9 seconds back! Get the picture!

    If you don’t drive fast go keep pace, then get the F*** off the road. So if you (the author) want to really save some gas, take the train and stfu.

  30. Anon wrote:

    “I have a simple rule – If I cant see your headlights and you drive a car, you are FAR too close to me. I slow down. The longer you tailgate, the more I slow down. I will continue to slow down until you pass me – which is all I want you to do. Get the hell off of my ass.”

    How about getting the f*** out of the way you jackass. People like you deserve to get run off the road.

  31. I can’t wait until automated driving, in which know-it-all tailgaters with aggressive tendencies and road rage can scream all they want, but the cars all stay at the same distance.

  32. RudePeopleInLeft says

    I don’t care what speed you go, just stay to the right so other people can pass. Simple. Efficient.

  33. I like it when people like Travis and Dwain tail gate me like a b*** in heat. I take my foot off the peddle nice and slow and coast in a moving road block next to the car on the side of me…… and then BAMM! I slam on my breaks and watch them veer off the road in a nervous rage and laugh while I drive away.

    Yea that’s right b**** check your pants, cause you just crapped in them, that’s right, that is that nasty smell on the side of the freeway.

    pwned!

  34. Anon, its people like you that cause accidents. Its people like you that are the reason my insurance rates are so high.

    If you want to be a dbag, be one on your own time. Be lucky I don’t do like dude and make you run off the road.

    In fact I think ill try that next time it sounds like fun.

    I refuse to endanger my well being because you can’t read a book on how to drive.

  35. noonecandrive says

    If you’re in such a hurry, you should have left your house earlier. If 5-10 mph (depending on traffic) over the posted speed limit isn’t fast enough for you it’s really not my problem if you’re running late. And this flow of traffic argument is superfluous, generally the tailgaters are NOT going the flow of traffic, they’re aggressively trying to pass everyone that is going the flow of traffic. They also often have a problem with planning their exits so you see them jumping across two or more lanes to exit because they had to get ahead of everyone.

    I won’t slow down if you tailgate, and IF there’s an opening to the right I’ll let you pass but I’m not likely to speed up for you if there is no opening. I’ve never gotten a ticket and I’ll bet all that aggressive driving has paid off in the tailgaters’ insurance premiums. Some time something will happen on the road ahead of the person you’re tailgating and you’ll end up rear-ending them. Speeding doesn’t really pay off in arrival time, in short drives it will be a matter of seconds at most. Happy high insurance premiums to you.

    My single request though is that people hang up their cell phones, no human needs to be driving and talking with a phone on their ear. That is a big contributor to traffic issues (studies have shown that driving while talking on a cell phone makes the driver as impaired or more impaired as a drunk).

  36. I have always followed the 3 sec rule, and if you tailgate me I’ll drive even slower just to annoy the hell out of you. The closer you get… the slower I go, and honking / flashing lights will just make it worst. I drive a Prius so I’ll go slower enough to use my electric motors, which is perfectly fine with me.

    The way I see it, having a gap in front lets people merge onto the freeway from the on ramps, thereby helping traffic flow smoother if everyone did it.

  37. All you people complaining about leaving space in high traffic conditions, should read this article:
    http://www.physorg.com/news117283969.html

    That’s right, it’s been mathematically proven that breaking unnecessarily is the cause of many traffic jams.

    Leaving space prevents over-breaking. It also provides room for you adjust your speed for proper merging, and allows people to merge without completely stopping everyone behind them in both lanes.

    @Andy: I hear you with those drivers that claim they’re aware of their environment.

  38. Engine braking may save you money on brakes but it increases wear on the gearbox and the rest of the drive system and i know which one i would prefer to replace

  39. More here.

    http://mark.tranchant.co.uk/2008/06/driving-more-economically

    Drafting (slipstreaming) is stupid, people. Don’t do it.

  40. And learn how to zipper properly. If everyone bunches together at lane merge/change locations everyone ends up coming to a dead stop while waiting for someone to make a hole for them. Proper spacing means there is room for people to change lanes without radical manuevering. The main reason people end up with improper spacing is #$%#’s who want to race ahead or butt-in rather than waiting their turn.
    Yet another reason traffic cops are worthless. Rarely do they catch the unsafe drivers, but instead catch the speeding drivers. And yes there is a difference. E.g. speeding on a lightly populated highway compared to weaving, tailgating, not paying attention, waiting till the last second to get into the correct lane, or just generally being an idiot.

  41. This is absolutely terrible advice. Let’s do some quick math. Given we are traveling at 60 miles per hour, which is equivalent to 88 feet per second. In 3 seconds, you would travel 264 feet.. Therefore, this is suggesting to travel 264 feet behind the car in front of you. That is almost the length of a football field. This is absolutely ludicrous!

  42. Hey rickblank. Can I go out on a limb and speculate that his tongue was in proximity of his cheek on the cutting fuel comsumption shaking out to better gas mileage. My leisure suits from the 70’s are highly flammable as long as they don’t burst into flames

  43. Bill good answer. Too bad we all live on another planet with “fuck you.” Pass on left. Kev, we’ll chisel that on your tombstone. Zeb, don’t let me catch you near my daughter. Pessimist. Half empty?..half full? Your half stupid. Still can’t be fixed

  44. Bryan. my guess is that automated driving will have governnent way involved. Or Bill Gates. Either way expect a lot of crashes. Dude. So your the one. I am closing in. Stay where you are. We need to settle a thing or two.”no one can drive”. Impeccable logic. Well thought out. Well written. Move out of the passing lane and its all moot. Better driver than you. I dumped my first wife in santa barbara in the fall of 1999 and drove straight to tiajuana to convalesce. Wedding ring is about even with LAX on the 405. Find it and its yours.

  45. “If you pull this crap during rush hour I will tail gate your ass until you move.”

    If everyone did this during rush hour, rush hour traffic would disappear. Everyone would have the appropriate time to react, and there would be no brake-slamming that ripples back 2 miles to cause stopped traffic.

    Pull your head out of your ass and your front bumper off my rear bumper, and enjoy a little less stress along with your gas mileage.

  46. I-294 Pace Car says

    “don’t want to get tailgated? stay the fuck out of the passing lane. (that’s the one on the left)”

    In certain cities, like Chicago, if your going to do less than 85, get off the highway. We don’t tolerate stupidity in Chicago, Especially the ass hole in the mini-van that thinks 70 in the left lane is not slow…

  47. OK four lanes. two middle lanes with no rush hour is where the bulk of cars should be. Even speeders. They go 70. You want to go 50. The guy who has a life and wants to spend it free of concrete and exhaust fumes overtakes the guy who is worried that breaking 50 flies in the face of god and will make you sterile. You can just not do a thing and not suck your underwear up your butt because there is no one and that means you… in the far left Passing lane. So we signal. We smoothly glide to the left. Before grandpa knows we are there, we are gone. Signal, and go back to the middle. Unless its all packed in. Stay in the passing lane till we are free of the bottle neck then head back to the middle.Even if you are going 100 head to the middle when its prudent. That way you don’t have to keep looking back for the guy going 102 because the passing lane is free and clear for him to do just what you did. But he will be passing you. Passing. Period. He is not mocking the size of your penis.He is just going a wee bit faster. If things are getting crowded the spill over goes to the right lane. but if you cast your lot there you must accept that you have to be deligent and stay on your toes and either head back to the middle on a temp basis or adjust your speed to let people on safely. But to live in the far right or left is to pay the dues for it. You can not exist there and fall asleep. You know that this is the place where all the action is, so you MUST keep your head in the game. You do not get to stay there and maintain the care free existence you enjoy in the middle. And If you like to go 50. and you overtake a guy doing 49.999 consider checking your mirror and deny yourself that rush you get by moving into the passing lane just as I was about to overtake and pass you both. The law of conservation of angular momentum says the energy spent overtaking the guy will be expended changing lanes. You know you don’t exist in a vacuum. Notice life beyond your bumper. Notice you cut me off. The energy of a lane change warms your tires and slows you. So sayeth johanne keppler. This NOW, with no extra energy added lets you NOW, match the speed of the guy you were passing. And you NOW, have the road block you gushed about. Its not the wreckless and negligent causing this. Its not the winner take all death race that you rail against. All you had to do was maintain your lane for one more second and swoosh. WE are here…and we are gone. And if you can’t gauge the speed we are overtaking you. Or if you WON”T gauge the speed we are overtaking you. You have no business on the highway. Its not for meditation. Its not for introspection. Don’t be pissed at your wife for not losing weight. Just FRIGGIN drive. We are driving. Actively engaged. If you DRIVE on the freeway what you see that looks so dare develish is safe. A lot safer than being dead from the neck up. And making up for your inattention by going 40 on a friggin interstate.

  48. Stickitinyagoozle says

    I drive a Honda Hybrid and take it nice and slow…in the slow lane. That is why we have slow lanes isn’t it? I can milk around 55 MPG out of going slow and I don’t give a crap about Bubba wanting to fly like a bat out of hell to get somewhere two minutes faster than everyone else on the road.

    When there is room in the left lane, I cruise under the speed limit a bit (in the right-hand lane) and make sure to slow down for the occassional asshole who wants to push me down the road. Learn how to pass people! This world is full of morons wanting to change everyone else instead of changing themselves.

    We humans are collectively stupid. We have our great big vehicles and jam our feet down on the accelerator pedals while bitching about gas prices being so high. Duh!

    Concerning the tailgaters of America, it’s all fun and games until you rear-end me. Then, I will make it my life’s purpose to sue the ever-loving crap out of you. With much love!

  49. Drafting big trucks may sound safer than cars because you can stop your car quicker than the truck can stop, but you don’t have that visibility of being able to see what is happening 100m ahead with that truck in front of you.

    I think a good tip for fuel economy (and driving in general) is “Watch what is happening not just with the car infront of you, but with the 10 cars infront of that”. Stop you from doing the alternating stabs of gas then brake

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