Drafting behind bus on for fuel economy(video)
 

My new youtube video with scangauge mpg reading
http://www.youtube.com/watch?v=HS-5LwKdq3w

Let's hope your next video isn't "crashing into bus causes bad fuel economy" :p

Looks to me like the bus might have just changed lanes in front after passing you, since it was steadily pulling away.

That's about the only time I get that close to (behind) another vehicle on the highway.

Don't say you're not only drafting, but using a camera/phone at the same time. Naughty, naughty.

drafting
 

yep it was naughty.Glad there was no mishap.Does kinda indicate what the car will do when aero load is shed.59-mpg is no laughing matter.Hey,are you Rick Wagoner -type people paying attention?

Driving, drafting, holding a camera, and blasting dance music all at once. Were you chewing gum too ?;)

Nice guages. Those aren't factory are they ? Nice scanguage setup as well.

Had you just let up on the gas when it spiked ? What were you getting before the bus was in front of you ?

That is a good song playing on your stereo. Unfortunately a fast song may make you drive faster and hurt MPGs.

If you see an RV with very low ground clearance in the rear(I can't tell here but theirs have those brush flaps, rubber flaps or something to catch rocks and its usually touching the ground) get as close as you are comfortable(and legal) and its thoroughly awesome.

I kind of hunt them when I have a drive of more than 100 miles. legally I can be two car lengths but even at 40-50 feet I can feel the wind shear when I get outside its envelope. I estimate a car length to be 10 feet, so if its raining and I have the top off I am right at 20 feet lol but the MPG is always good for that trip despite having the top off.

I've done this and it works well, but the bus was trying to shake me and kept changing lanes. You can definately feel when your "in", as you can lift quite a bit off the pedal and won't lose speed.

If you have a smaller lighter car, it can be dangerous in the rain. The difference in the air speed just outside of the envelope is alot higher and if the driver in front of you changes lanes abruptly or wriggles it can send you skidding left or right.

Its happened to me so.

Other than that I'm a pretty big fan of legal drafting.

Trying to be diplomatic

I hope there is a disclaimer on drafting, that it's not endorsed but just to illustrate the power of good aerodynamics.

Drafting is effective - geese do it, squadrons do it. In 2000 an editor for Car & Driver poked inches behind an Explorer with a plywood board blocking better than an 18-wheeler....at 58mph on a warm day I might get as good as 85mpg, but he got 121mpg. Two years ago I noticed a 7F rise in coolant temp. I don't do it anymore - ever.

Hypermiler-bashers are doing their darndest to say drafting semis is standard procedure, but I have yet to know of a hypermiler that has done it the last 1-2 years. At Wayne's site we empatically discourage the practice. I've lost count of hypermiling articles that at the end have it advised against by state trooper that likely have no clue to hypermiling and some articles are simply and OP/ED against it posing as reporting with wild accusations of hypermiliner doing rolling stops, pulse and glide in rush hour traffic, etc. If you took them serously, we are up their with sucide bombers, but wait a minute. If there was ONE accident that could be linked to hypermiling, it would be news, yet 100-110 Americas die on the roads due to speeding, DUI, distraction, recklessness.

There is too much traffic to do this in urban areas long enough to benefit significantly. Now that truckers are aware, many will vary their speed, etc to shake tailgaters off.

Anyway, please make this an illustration that it's effective but not recommended.

If you want to reduce wind resistance, aeromod.

No one here including the OP is advocating to get on their bumper. I'm the only person who even advocated doing it at all, and even then I said be safe and legal about it. If you are doing something safely and legally. . .there is no reason not to.

Its pretty simple. Staying behind a semi/RV/bus regulates your speed and they are far more cautious(on the average) than anyone else on the road. They know that the several tons of cargo won't stop quickly so they watch ahead. If you are a safe distance behind them. . . its safe.

I stay safely back but at the same time I'll stay behind them as long as possible(I have a 200 mile drive once every 2-3 weeks round trip and I'll do it both ways.)

The people behind me are much closer than I am to the larger vehicle, cops are alot closer behind me than I am to them. I can safely break much faster than the larger vehicles and I can usually see around whats going on.

As long as you maintain a safe legal distance away drafting is fantastic.

I tried not to sound shrill or the like.

As long as those on the fence on hypermiling or even oppose it know drafting semis is not a condoned practice by hypermilers themselves, no problem.

I don't know about you guys; but if I follow that distance my biggest hazard is the the people who pull in between me and the bus.

The way "I" figure it is if someone feels that there is plenty of room between you and the leading vehicle to cram in then you are ok; now WHEN somebody crams in you'll have to back off.

Now operating video camera and drafting isn't a good idea.

Unless its mounted on switch is you do. . .or the passenger operates it.

Dremd oddly thats usually how I decipher if I am close enough or not. I try to make it big enough for another person but to make it not really invitingly large

I "assume" it on a switch is the Video Camera?
I'm mostly joking about the camera, but it is dangerous to be operating a handheld camera while driving.

I'd live to drive that way; but so far I "feel" if I follow close enough for nobody to merge in I'm 2 close; I could be weird, or maybe drivers are more aggressive around here.

Drivers around here aren't that aggressive and its usually 2 lanes so the aggressiveones can see its not likely to get them the 10 feet ahead of me the left lane will get.

Have you looked at the hypermiling board? People do the rolling stops, etc etc

Coasting to a stop is fine, but rolling thru a stop sign is not.

Over the past two years, opponents have misrepresented hypermiling by dwelling on semi drafting and rolling thru stop signs to discredit. It would be just as factual to say all motorcycle riders are street thugs like Hell's Angels. :rolleyes:

Most of you know the forum I hang out - it's not recommended there.

PR is important - let the hypermiling-bashers be the crazy ones.

Just aeromod your car to the point to where drafting produces little improvement on your mileage, then the whole drafting/safety discussion is rendered a non-issue. If all cars were shaped like mine, then drafting would be irrelevant to improving mileage.

oh noes! someone did something dangerous! let's all get upset and make disclaimers about drafting!


seriously. You people.

Don't be so dismissive - Google hypermiling and there is numerous accusations (unproven) about drafting, rolling thru stop signs....and hysteria that make hypermilers seem more dangerious than speeders, drunks, druggies, cell phones...and it's spoiled brats that are afraid if more people slow down they can't with impunity drive like Hell.

My only comment is I don't have the assets, the ability or the time to mod my car to make drafting irrelevant.

Even so alot of the time people here claim the idea is to also reduce the total amount of fuel used in total. Drafting off of people decreases their load even if only marginally.

a million times a tiny number is a much bigger number. seriously if it even improves the person in front of you .01% and everyone does it(Atlanta has something like 3 million cars so half of them?) (at just 12,000 miles a year avg of 23 mpg for 2 million users(just the lead car recieving boost from the rear car) Atlanta saves 104400 gallons of fuel. There are over 300 million people in the US and if 1-6 has a car and every other of those has someone following "helping" it saves 1,305,000 gallons of fuel over a year.

Its no small matter. If FE improves for either car a one hundredth of a percent and everyone does it(the stupid way not making smooth chains with safe distances between each, but in pairs) the US uses 1.3 million fewer gallons of fuel.

Now factor in the notion that the rear car is getting an FE improvement and. . .

Once again (in a calm voice) - hypermiling is not drafting. Hypermiling is tools like planning your route to drive accordingly, pulse and glide, drive without breaks, timing stoplights, maximize the use of gravity (including accelerating before approaching a hill).

My morning work commutes with the Insight started in the low 50's....recently I got 115mpg - without drafting.

Is doubling the mpg good enough? Even 30% is not bad by hypermiling.

Who has cable? Who has a cell phone with a data plan? Who has car payments for a car that requires hypermiling to get good FE? Cup of coffee you bought? buying lunch instead of bringing? I stop now, I sound like treehugger.com.

There are so many things one can cut from their lives--the luxuries--instead of trying to squeak that extra few percent for higher FE. I certainly am not dismissing hypermiling, it's a useful tool. Drafting is part of that. You get can get 115mpg from a 50mpg standard-that's great. Congradulations, seriously. I wish I could do that in either of my vehicles. But I can't, they don't have the equipment for me to get that. So I use all the tools available to me, including drafting. Drafting can increase the mileage on the truck by 2-3mpg. Unsafe? It might be, but for me it isn't. I know my limits and the limits of the vehicles I draft. I don't draft vehicles I think will be unsafe for me or those around me.

If the owner of the video knows his limits, it not impossible for him to hold a camera and draft a bus at a distance. Some people can't, I acknowledge that, but some can. Every drafting thread started on here has naysayers saying drafting is dangerous and bad. It's not. Stop generalizing. It's annoying.

Gauges are stock and I was chewing a gum as well :cool:, thanks

I let up gas a bit and before bus I was getting around 50 mpg at the same speed. When I slowed down to 55 mph load increased and mpg went down to 45.

If there was a 10 dollar bill would you pick it up off the sidewalk? If you could reduce the amount of pollution you produce at no cost wouldn't you?

Draft.

I already said it but to really put this in perspective the person who you are drafting off of gets a bonus in mpg as well.

a .01% bonus on every other car in the us saves 1.3 million gallons of fuel or 2.6 million dollars.

Drafting allows me to hold my throttle just slightly higher than idle and cruise at 65. I'm using virtually no HP. The last few trips I've managed to find an RV this last time and a Semi the time before that stayed with me for 180 miles. Over that range I used 3.7 gallons and 3.8 gallons(48 and 47 mpg respectively). Either way thats a 38% improvement in FE.

I'll be conservative and I'll just say 10% for the purpose of calculating how much fuel is wasted by not drafting for the average driver.

1185978261 gallons of fuel per year in the US(Assumed avg vehicle gets 23 mpg, that only half of the cars would get a bonus, 50 million cars total, goes 12,000 miles a year, and a 10% increase in FE for the following car) plus the 1.3 million gallons saved by the car being drafted off of. And thats a modest estimate considering I can get 10% off of another small car(Civic 2 dr) and there are plenty of large trucks, rvs, SUVs and regular old trucks. Also if you link those chains at safe distances all but 2 of the cars get a push and hide inside someone else's envelope.

It is ecologically and economically responsible to draft at safe/legal ranges. If you aren't comfortable with it then its unsafe for you, but if you are then by all means be careful but do it.

Berkeley did a test that used small magnets embedded in the highway along with a radar gun at the nose of the car. The lead car followed the magnets and the following cars just had to stay exactly 21 feet behind the car in front of them. They did it with 7 cars and outside of standard cruise control they showed there was a substantial improvement in Fuel economy just from a Buick Lesabre drafting off of another Lesabre. They also tested the system at 5 feet and the results were much better but very few people could maintain that distance without burning up extra gas.

While equipment (i.e. a good fuel efficient car) is important - so is good technique. My testimonial of going from around 55 to 115mpg on morning work commutes...more typically the range would be 70 to 95mpg. Yes, that was about a 100% improvement, but anyone here can get 30% better without going to the edge - seriously. If you're not exceeding the EPA or plateauing on fuel economy, two things will help (1) start a thread and let members examine what you are doing, (2) read more on the techniques of hypermiling.

That morning commute is posted at 60mpg most of the way. I did 70-75 and now it's 45-55. I do the trip before rush hour - can't do it when traffic is heavy.

My hypermiling is not just technique or mods, but a steady change in attitudes and behavior. What I've found it the more a person feels they must keep up with the pack (in general: speed with the rest), the harder they find hypermiling and sometimes the more they dislike hypermiling. A number of speeders are trying to intimidate. Yesterday, a dump truck was highbeaming and tailgating me. He did not get to me. What do you think is going to happen to his job if he rear ends me? ;) BTW, dump truck definitely have the worst drivers of big rigs - how do they get their CDL? At least a 100 yards behind me, he saw me tap my emergency flasher - plenty of time to find a chance to pass in one of the two lanes to the left. No, he spends at least 45 seconds attempting to kick my butt before passing like he should have done to start with. In most instances, the really bad tailgaters have some kind of behavioral issues - flagrant speeding, very short attention span, anger....it's not about my driving, but his driving.

Hypermiling is advanced defensive driving - knowing what's ahead and what to do. It's also not letting bad driver such as that dump truck get to you. Kind of like you're a quarterback and three 350lbs lineman are racing at you. You're going to get hit anyway, so concentrate on completing the pass.

I'm getting 70+ mpg these days, with no drafting. I would have to speed up to catch a draft, since they're going faster than I am, but why would I? It would cost me more fuel to do that.

We have to be careful about the message we're giving out. If we want others to drive more economically, our ideas have to be something they'll accept. If there's a single sticking point, they'll reject the whole batch.

Drafting, even with explanations about doing it safely and keeping following distance, is one of those points. People hear the word, and the picture they have is of parking inches behind big rigs. I actively recommend against it, for that reason. The listener will likely not hear the details after the single word, "drafting". I don't want to be responsible for them to misunderstand me.

Again, really good fuel economy is three things: (1) good car (mods help), (2) good technique, (3) ignore the speeders and ragers. Actually you can get pretty good fuel economy with a car that is not all that fuel efficient.

It's worth repeating again: the more you feel like you have to keep your speed with the pack, the harder hypermiling will be. Two reasons for that. The first is on a graph of wind resistance, it takes off above 45mph, so if you do much of your driving above 60, it's going to be hard to get good results. If you vary that throttle - good fuel economy is almost guaranteed to not happen. The other reason is allowing speeders and angry drivers to drive like them and fillup like them.

I live in the Dallas area. Drafting on a typical commute is overrated. To effectively get better results, the semi needs to be going steady in the 50-65 range - unlikely in a city like Dallas. Outside cities, there are more opportunities, but truckers have been alerted to drafting and they often defeat it by weaving, changing speed, etc.

If you are three or more car lengths from the big rig, then it's not the type of drafting that has been demonized in the media.

Take inventory of how you drive and it will improve.

But it uses the same title. This leads to confusion and misinformation.

Andrew,

Sorry if I appeared to be passively endorsing the D-word.

Was attempting to say, make sure you are clear of a rig's "No-Zone" so everyone has a clear field of vision.

What I see (and experience) daily is aggressive drivers bolt from car to car tailgating and rabidly pass to tailgate the next car.

No, no. I was merely highlighting what I consider a key point of your text.

I definitely will not say something if I think a reasonable person is likely to misinterpret it or misunderstand it.

Drafting as I said is not one of those things. Before I even say the word draft I always say "I stay more than 2 car lengths back always, but I like to draft. . ."

I also live in Tennessee and our truckers don't care. They do it to each other much more so than I do and if they see me come back there they will always signal far in advance of making a move. Likewise I always communicate with them when I can. If they put on a blinker and there is room in front of me I flip my lights to say its all clear.

My FE is 25% above my combined for my city driving(I only have short city hops during the week). My normal tank does 35, but if I am highwaying without a truck escort I still can punch 37. I'll be the first to tell you my transmission is geared too low.

Also drag doesn't really take off. Its a quadratic with no inflection points. Its a pretty big deal at 20 mph for a bicyclist. At 30 mph its a considerable force for a car.

One of the single most effective proposals to eliminate the need for high speed rail is to install on the HOV lane a magnetic strip. As soon as you want to insert your car into the lane click a switch the car closest to being behind you decelerates just enough to allow your car in. your car catches the line sends a radar pulse finds the car in front of it and tada, each car can draft inches away from the car in front of it safely.

Lets just imagine that except for the lead car this more than less eliminates drag( at out speeds its pretty close but at race speeds its not so close). It requires 9 horsepower to overcome drag at 60 mph. My max is 101 hp at 6400 rpm(?), I'm barely pushing the gas down at 3000 rpm, but even if we assume I'm WOT at 3000 I'm still using 1/2 fuel and producing roughly 1/2 the power. 50 hp-41hp/41 is a 21% improvement. I can assure you its not anywhere near WOT so its going to be alot more than that.

We all want to improve our fuel economy and encourage others to also do the same.

I'm talking about setting a good example to the public and avoiding bad PR.

Last summer, many were intentionally spreading myths to discredit hypermilers. It's copycat reporting, bad reporting, and even slander.

Check out this link - it's Google: "hypermilers drafting"

A year ago, there was a hypermiling event in Washington state. A Channel 5 reporter did a 90 second shoot of Wayne Gerdes - that part was fair, dispassionate. Afterwards, the reporter added another 90 seconds throwing Wayne under the bus...had a trooper who probably had just heard of the term making this sound like this is more dangerous than DUIs. That's just a worst case of reporting.

Brief tangent: a word for "stingy" is taboo...it sounds too much like the N-word...has nothing to do with a serious racial slur, but that's what people think so it's not used anymore. Drafting is another such casualty.

You may be safely behind someone and benefit from their lead, but I avoid the use of the term drafting as the propaganda implies it driving too close to see the traffic or to stop safely, even in this instance. Call it surfing or something else.

fine by me.

I surf car wake!

Hi Unchosen...,

I think you need a Chirp CW radar for that application. A pulse radar would need to be expensive to have the range gates as small and as often as needed. I would avoid drafing without such an aid. But to be sure it works, you will need a test track and a willing lead car. The new Prius has an optional radar cruise control. Also, that 77 GHz stuff is kinda expensive in small quantities.

Hi Delta...,

I remember that. They showed a car drafting a big rig that was not even Wayne driving it. They used a sly technique to imply that it was Wayne. They were talking about the Insight, while the Saturn SL was there on the screen tail gating the semi. Wayne was in the area to demonstrate Insight techniques, and the short bit with him was in an Insight.

Hi All...,

In the Prius, it gets best mileage when its going along very stable-y at about 53 mph. When a Semi comes up next to it, the bow wave will drop the speed 1 mpg, which drops the mileage from about 72 to 65. Once you get back up to 53 mph, you can then feather back the throttle and have it lope along at 72 mpg again. The main problem is the sideways wind flow is like a cross wind. Which increase the aero drag. Along the side of the truck, the boundary layer of the truck is so low-energy, that its turblent, and screws up the Prius aerodynamics. And the Prius has such good aerodynamics it does not get much benefit from astern drafting at 65 mph (what trucks do around here in the 55 mph zones), that I just stay at 53 mph in the far right lane. If I see a truck coming up along side, I get way over to the right to avoid most of the bow wave and turbulent side air.

Once upon a time, long, long ago, I was slogging through slush, stuck in slow traffic and low visibility, when I got spattered by a Greyhound with schedule on his mind. I jumped on behind and had a great run. There were just enough holes in the traffic for someone with a high seat to maintain speed. I probably saved gas, as well as time.