Reverse drafting: how to slow down on the hwy and not hold up traffic
 

As everyone here knows already, probably the simplest way to increase your fuel economy significantly is to reduce your highway cruising speed (NRCan quotes about a 1% increase in consumption for every 1 km/h over 100 km/h).

Despite this fact, I have noted that people sometimes instinctively recoil from the suggestion, citing "going with the flow" as the reason.

I often wonder how much of the objection stems from the practical (ie. actually significantly disrupting traffic flow), and how much is psychological (the stress generated by the inevitable tailgaiters, who inattentively ride your rear bumper for a while, then "wake up" and roar past).

Regardless of the root of the objection, my prescription for people who are sensitive to the issue of slowing down is this:

Enter the freeway at your usual pace, and drive as normal until you pass a transport or other large vehicle in the right lane which is driving slower at a steady pace. Change to the right lane in front of that vehicle (keeping a respectable gap of course). You are now free to drive at the reduced pace of the vehicle behind you. You are no longer responsible for blocking faster traffic; it was flowing around this vehicle anyway.

It's sort of "reverse" drafting: they're breaking the flow for you - not of air, but of faster traffic approaching from behind, and you're capitalizing on that to improve your fuel efficiency.

Sure, but what do you do when the truck (if it's a truck) speeds up going down hills?

I didn't say so in my original post, but I adjust my speed to match the vehicle I'm reverse drafting, including trucks behind me on hills. Common courtesy.

I also speed up for trucks approaching from behind if I'm driving slower than average - solo - if they don't have an immediate opportunity to pass me. Once they're by, I drop down again.

And this strategy may not be practical using heavy trucks on hilly roads.

It's good advice to follow. The hard part is getting people to see the light that all the little things add up into something palpable.

Every road I drive on has two lanes of traffic going in the same direction. I always stay in the right lane and go the speed limit. The highest speed limit on my route is 65MPH. I will go up to 65 since it's only for 2 minutes of my commute. The rest of my trip is spent at 55MPH. Even going the speed limit I'm passed often. The only thing is: I don't feel bad for making people have to pass me since A) They are the ones going beyond the speed limit, B) They have a passing lane and have plenty of time to see that I'm not speeding since there are no hills on my route, and C) They have a chance to see my license plate frame "My car is slow but 50+MPG".

If there ever is a semi barreling upon me, even above the speed limit, I will make sure that they are able to pass easily.

Also, when I get passed by a semi and they want to get in front of me, I make sure to signal to them by blinking the high beams twice. I always get a great response from the truckers with the parking light flash from them. I also do this to let them know I see them and it is safe to pull in front of me from a merging/on ramp lane.

Your post is more evidence that proves ecodrivers/hypermilers have an above-average awareness of what's going on around them.

We may drive differently, but we're considerate, and the awareness of traffic probably makes us safer than average.

I purposefully drive 65 or under because I love looking into my rearview and seeing the people swerve to look around as their faces turn red.

If the tailgating irritates me or if I anticipate it I just adjust my rearview mirror so I simply don't see them. They usually just zoom past me and give me a dirty look while I laugh.

whoops...

/me runs and hides.

On a normal note, I am considerate but I get over when it's safe for me, not when it's convenient for them.

MetroMPG -

I am definitely in the "go with the flow" tailgater stress excuse category. Your idea is interesting, but for me, I would still drop in behind the slower vehicle. Once I am behind a slow-poke, I stop worrying about tailgaters because they can't blame me for driving slow ;) . Also, it's easier for me to follow a slow-poke than it is to keep tracking their speed from in front.

CarloSW2

It seems to me that reverse drafting is inconsistent with attempting max fuel economy. It is always better to follow another vehicle than to lead and have to "break wind". If you are going at the same speed anyway, why not follow and gain the draft? Ever try bicycling over a distance in a group? The lead rider tires quickly and must drop back. Let the guy ahead buy your fuel.

On the way home from work, when the freeways are alot quieter, i have started going over to the slow lane and then using CC to let my car keep itself at 55mph. It may be bad to use C. Control, but if it keeps me from doing 65 on a dead highway than why not?

I missed this thread :p

Funny thing is - despite whatever some ass might tell you about truckers "feeling" parasitic losses from tail gaters... There is a very slight aero advantage when there's someone behind you as their high pressure fills in your low... Of course, someone in front is better - someone behind is okay - worst possible scenario is no one around you...

In fact, iHPVA rules state that chase cars must be at least 200' (not 100% sure on the exact number) behind the HPV on the course due to this advantage :)

Trucking and You
 

On my most recent long distance trip, I followed a Tractor-Trailer hauling grain, which emulated my average commute (limit = 70 mph, truck was driving 60, slowing to 55, up to 65-70 on downhill). Behind me was another semi that would gain and loose on hills.

This was a great situation. I could DWL on the hills with the truck ahead (little-to-no drafting: 4-second following distance), and the truck behind used the truck ahead as the "cause for slowdown". Eventually, the semi behind became impatient and passed us both on a long downhill.

I prefer to follow the transport ahead, if too momentum isn't lost on my part, on the uphill side. This best works with 3 lanes. Passers can pass, and those who enter/leave the highway can do so without impingement. I get pretty nervous with large trucks on my arse after a while -- especially when they can't pass. If I can read the rig's brand name in my mirror, then that anxiety builds...

RH77

MetroMPG -

I tried your suggestion the other day and I think it worked, but I spent a lot of time looking in my rear-view mirror to make sure I maintained the same speed.

While I was doing that my over-kill-engineering brain began to work overtime. I wanted a radar system similar to a backup radar that would maintain a dynamic cruise control by "locking" onto the slowpoke behind me. I wanted it to be programmable based on seconds, aka maintain an x-second gap between me and the car behind me. That way, I could spend more time looking forward. I think this has already been done in fully automated self-driving car experiments. If you wanted to be a follower, you could flip the radar logic to work both ways, for a car either in front or behind you.

CarloSW2

If there are three lanes on a highway, then the slow lane can damn well go 80km/h (50mph?). If someone doesn't like it... they can damn well pass. I don't need to apologize, feel sorry, or timidly accelerate every time another car approaches to go under the speed limit (so long as it's over whatever the minimum speed limit is).

Tailgaters are the best, and those who like to flash lights or beep the horn (I only get those last two maybe once a week to once a month). For those times, my right foot gets oh so tired... oh, you had to use your brake pads because you were too stupid and accelerated without thinking? So sorry! :cool: And what are you going to do about it, dumbass? Are you going to bump into me? (But... your honor! He was going 80km per HOUR!) Don't think so! I'll just coast down some more and make you madder! It cracks me up so much! :D

Especially when it's a big SUV or semi behind me... they must think that they are a BIG MAN! Do they think I'm a motorcyclist and am going to worry about slipping over and getting crushed by a heavy vehicle, and so be intimidated? Don't think so! Hell, my boattail would probably absorb it anyway and push me forward a bit. Encountering someone this homicidal would be extremely uncommon. If they were going to attempt manslaughter based on someone going slow on the highway, in full view of a mass of other cars... I mean, come on. Most people encounter someone going 20km/h below the highway speed in the first hour or two of driving.

Let's do the math... I have to encounter someone who
-is ragingly impatient
-is homicidal over petty things
-has absolutely no fear about serving most of their life in jail
-has not already killed someone and went to jail in their first week of driving
-has not already killed someone who looked at them the wrong way, in a crowded room full of ready witnesses, before they even had a car license, and went to jail

If you are worried about that, I'd keep an eye upwards for stray meteorites as well.

Of course, it would be a completely different story if I was in the fast lane, going 80km/h while keeping exact pace with my neighbor, preventing anyone from passing. But I don't.

I should really put something on my bumper such as "3.5l/100km" or "Recession Proof". I'm hesitant about the last one because some almost bankrupt person with an SUV and a $400,000 mortgage they can't pay for (purchased so they can have the house and vehicle just like all their friends) might get more envious, angry and homicidal than a little tailgating might provoke.

Yeah, I know your thread is directed at those timid folk who would rather waste hundreds of dollars a year, waste resources and wreck the environment than have a stranger disapprove of what they do. I just felt that it was necessary to affirm that it is your legal right to go whatever the legal speed is on a highway, and morally, if someone has a problem with your speed while you are in the slow lane... the problem lies with their faulty understanding of how multi-lane highways work.

Technically, you're right, Newton. However, I have seen a case of 2 motorists who were charged & convicted of obstructing traffic for driving the speed limit, side by side in two lanes. Some laws are more sujective than others. Just putting it out there.

Well, thats just inconsiderate Metro. Pass if your going to pass. Otherwise, slow down and get behind or speed up and move over.

I'm pretty stubborn most of the time when driving. I'll go the speed I want to get good mileage. I won't hold up traffic, but I sure as heck won't speed up for a tailgater. I pay for my gas and until someone else is buying it for me its my money going out the window, so they can pass or slow down.

True about being inconsiderate, Daox.

My point was more that a strict legal position to defend your choice of speed isn't fool-proof when there are other more discretionary laws that can be applied as well.

If someone was convicted of obstructing traffic, it should have been the guy in the faster (center-most) lane.

If you're going to go slow, use the slow lane. Going slow in the middle or fast lane will be considered inconsiderate until the demand for slow speeds increases to the point where they won't all fit in the slow lane. You should be able to get an indication of this point when the majority of people who use the slow lane by default will go below the speed limit naturally, without anyone in front of them.

On a slightly different note, most people think of highways as being ways to get to a destination quickly. They are that, but the other advantage is lack of unplanned stops. In many cases, you can get to your destination on the highway without any loss of kinetic energy at all (braking).

And on another note, sorry for the road rage above. That morning I was tailgated by a truck, who zoomed past me only to brake heavily at the exit.

I got another one for you...

About a year or two ago I took a 1,300 mile trip and since I have a perfect driving record I always set the cruise control to do the speed limit. Lo and behold, doing 65 constant I must've been in the 1% of slowest cars on the road, these fools were passing me 70, 75, I think I am sure 80 and 90 it was ridiculous the entire way this load of crap!

Now some folks can disagree all they want talk about I'm holding up traffic but my attitude is the speed LIMIT is the absolute fastest we're allowed to drive, technically speaking we should be slightly below even.

Either way, I learned a new technique in this process, I call it working my way backwards through traffic. Takes a lot of studying the rear and not more than moderate traffic, also it works best to do it only for tractor trailers and such and let the rest of the cars fend it out on their own... But basically what I would do is change lanes when something was coming up directly behind me and if the other lane was clear, again more so with tractor trailers than anything else.

And believe it or not as the 18 wheelers would pass, now I don't believe in tailgating so they were just passing aside me, even then I could feel myself benefit from the passing wind, yes, I could FEEL it.

It was great, a true masterpiece of driving, the cruise control stayed engaged most of the time and the police was heavy that day and more than a few got pulled over as I just MYOB as they say.

(I know I'm little late jumping in here but I just had a thought)

Wouldn't it be more efficient to just stay behind the semi? I know it's more dangerous being behind one to some extent because it's harder to see the road ahead and depending on your distance, the driver of the truck can't see you. But those things aside, from a pure efficiency standpoint. It would seem like being behind the truck would yield more aero benefits then being in front and you wouldn't be holding traffic up anymore. If you are directly behind a semi, people are not going to assume that you are holding them up because they know that trucks go slow so they will just proceed around as normal. To top that you benefit from the hole he just punched in the road for you.

The idea is to slow the traffic behind you just enough that they don't feel the need to pass and stay in line at a lower speed. Efficiency wise - this prime. You're increasing the FE of more than one car rather than increasing the FE of just one car (yours) :thumbup:

Here's for anyone still having trouble going slower on a highway:

Why worry about people passing your car? Can worrying add a second to your life? Isn't it better for them to pass you anyway if they're tailgating you, Only to find out they still tailgate you above the speed limit which is even worse? If someone tailgates at any speed, They're tailgating even if they don't do it at another speed so it's advisable to encourage them to keep a good distance from your vehicle in whatever means possible, Even if that means allowing them to pass you.

In most instances I've seen when going 55 in on a highway, Nearly every car and semi passes (I don't recall as many as five vehicles staying behind me for a long time since I started doing this months ago) and then there were scarcely any vehicles around until the next batch of drivers; Most drivers I've seen seemed to be traveling in packs.

I've found that no matter how fast I drive the person behind wants to go faster, so I've stopped caring about holding people up.

I notice that I end up between the packs, especially at night. One in front, one behind, with a huge gap in between with nothing but my little tiny Yaris in it.

Occasionally some a-hole will need to shoot the gap at 240MPH, but for the most part I just drift along in my own little world. It's really kind of nice.

That's what I do...

Even then it sometimes manages to grate on my nerves.
When that happens, I usually slow down.
And keep slowing down.

The intent is to encourage the tailgater to pass.

Strangely enough, a good half of these glue balls stick to my bumper until we are both at a complete stand still.
Even on 55 mph posted roads.
With traffic everywhere.

You can call me an unsafe driver.
You can call me insane.

But then I just stopped caring, too.

Sometimes I switch over into a "faster" lane and pass myself for them. With me out of the way, they will often speed up. Then I switch back into my own lane and resume not being an ***hole--unlike them.

Our local freeway used to have a 55 MPH speed limit, which they changed while I owned my first car. Between my tires riding roughly from overinflation (they ended up falling apart) and other problems with my car, I did not feel safe driving faster than fifty-five, so I maintained that until I was stationed in Germany. If someone comes up behind me, I may change lanes to get out of their way. If they tailgate and become a nuisance, I will probably shift to neutral and wait them out. If they turn on their high beams I adjust my mirrors accordingly--I really do not like brights!

Back before gas reached the prohibitive price of two dollars a gallon people would find out that I drove 55 MPH and start yelling at me, which only provided amusement--this was only an academic problem, but they always told me that I obstructed traffic, and somehow I would be ticketed for that while they would not be cited for speeding.

Well, at least for the first four weeks of each month.

Honestly, though, I am not under any obligations to become an accomplice to a crime. If people want to speed, I am not going to try to prevent them, but I am not going to enable them.

Besides, if they are not getting better mileage while behind me, they are doing it wrong!

When I have occasion to pass people it can be complicated because they may not be using cruise control, they may speed up for whatever reason (like character defect), and if the slope changes, I may lose some speed relatively. I sometimes have people stuck behind me as I slowly pass.

I hope that I live longer. I feel like I put myself through much less stress as I drive. I just try to relax. Wherever I am going will still be there whenever I arrive and I might not really want to be there anyway.

What frustrates me are city streets. He who spends the longest waiting at a light wins? I believe that I mentioned before the time that I drove a minibus past a mall. Some kid in an old Japanese car with modifications resulting in more annoyance than performance kept accelerating hard from one green light to the next red, only to have the same minibus catch up at every single light.

True, I was thinking of single lane highways but it amazes me too...
The tailgater has a perfectly useful faster lane devoid of traffic.
All they need to do is switch, and be done.
But, they won't.
They'd rather stay glued to the bumper of my car.

On a less drastic scale that is how I find most folks driving, like the kid in the Japanese car. Just because they didn't accelerate full throttle doesn't mean they didn't tunnel vision the traffic light up ahead.

I will try this next time,i rarely see any large trucks when driving to my commute though lol//.:thumbup:

I get a bit frustrated anymore when some jerk tailgates. I drive the speed limit (55mph) on two lanes and the same 55mph on the interstate. I still feel that it's not my fault they didn't leave enough time to get to work and have to break the law. I haven't heard of anyone getting cited for driving the speed limit but in this mixed up crazy world of "entitlement" I'm sure it happens. They post a minimum speed limit on most roads. I think it's usually 45mph even on the interstate. If you are going more than the minimum even if you are going under the "limit" (like 55mph on a 65mph road) I can't see it holding up in court. Just sign the NOT guilty line on the ticket and then make the officer explain exactly just how you were breaking the law in court. As long as you were in the right hand lane on a 3 or more lane highway or at least going the speed limit on a 2 lane they don't have much of an argument.

I can usually wait them out because I also just don't care too much anymore. It's when they get too close that I just start to practice my PnG techniques. Practice makes perfect you know. ;) The ones who choose to ride my bumper with their brights on don't like it for very long because I have found the right angle with my rear view to throw most of the light back at them. "But officer...it must have been dumb luck that when he wouldn't turn his brights off and I reached up and slapped my mirror that it directed it mostly back at him blinding him while he was trying to blind me."

I have been known to ever so slightly press on the brakes. Just enough to make the taillights come on. I wouldn't slam on the brakes because I don't want to wreck MY truck. This and the mirror thing are really only reserved for the extreme jerks out there. Usually I wait them out and as the go roaring past me, telling me I'm #1 with a little finger gesturing, I just give them a big thumbs up and smile. Does this make me a "bad" driver? I really don't care anymore. I was a "good" driver for 25 years and "went with the flow". But now at $3-$4 a gallon for gas and a 120 mile round trip commute to work, they can just kiss......................

Reverse tailgating is hit and miss in most circumstances, getting behind something slow is always a winner. You can "draft" if you are into that kind of thing (debates elsewhere) but if not you have something obviously big and slow in front which means those coming up behind can see it and change lanes before they get to you - which means fewer tailgaters.