Mythbusters Drafting episode [Archive] - Toyota MR2 Message Board

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Dance_Business06-10-2007, 10:45 PMWARNING DO NOT TRY THIS!!!!!
Drafting a semi truck increased fuel economy by as much as 39%
100 ft = 11%:)
50 ft = 20%:D
20 ft = 27%:lol:
10 ft = 39%:shocked:
2 ft = 28%*:wtf:

* the difference at 2 ft was accountable to feathering the throttle to maintain the distance.
Pretty crazy! mr2slow4you06-10-2007, 10:47 PMI think your numbers are off a little? I thought at 10 ft it was like 44% and 20ft was like 41% Dance_Business06-10-2007, 11:01 PMThat was mpg. Here's the link to the extra footage, web only. A bicycle drafting the truck... (http://dsc.discovery.com/search/results.html?query=big+rig+myths&go.x=0&go.y=0) I drafted (when I was 16 and STUPID) a truck from Gastonia to Charlotte at about 80mph, my car was in neutral about 1/3 of the time... I knew this one worked. Don't ask how close, as previously stated: I was 16 and STUPID! Weasy2k06-11-2007, 12:50 AMwow i knew it did something but that much! PETC06-11-2007, 01:55 AMI try to draft as much as possible. I never need to get anywhere too quickly and it works really well. Tommy122306-11-2007, 03:12 AMbut then you get rock chips. I'd rather pay for more gas than get rock chips. PHOENIX06-11-2007, 03:13 AMsomeone please explain drafting mr2slow4you06-11-2007, 04:44 AMWhen driving, you are in a huge chunk of mass. Thus chunk of mass has opposition to its inertia, air resistance. Since we are not in outer-space out environment of air is comprised of different gases which have a density. It requires more and more force to overcome these particles.

In drafting, you have an object that is not connected to you that is breaking the air for you. Imagine putting your hand outside the car when your driving, not doubt you can tell a difference between your hand fully vertical, creating a wall, and fully vertical, creating a narrow plane. Now imagine taking your hand fully horizontal, creating the wall, and place your other hand behind it. You would have to provide some force to keep your first, horizontal hand, stationary. But, you wouldn't need to apply nearly as much force to the second hand, since the first hand is disrupting the air flow and breaking it up before it reaches the second hand.

I just got up, so I will re-read this when I am more awake:) PHOENIX06-11-2007, 06:09 AMoh

So in english, if you drive behind a semi truck really close, you get better gas mileage because your not having any air to push through with your car. mr2slow4you06-11-2007, 07:35 AMYa, that sounds pretty good. Not necessarly zero air, but substantially less.

I wonder if the radiator will get enough air flow for extended amounts of time of doing this though. mopwer06-11-2007, 07:49 AMYa, that sounds pretty good. Not necessarly zero air, but substantially less.

I wonder if the radiator will get enough air flow for extended amounts of time of doing this though.

The car doesn't have to work as hard so it doesn't need as much cooling.

This tends to piss off truck drivers since you have to get soo close. Plus if they have to stop suddenly, you're looking for a new car...

Greg Davis06-11-2007, 08:01 AMOr a new head...

I'm scared to drive behind trucks! That bar that hangs in the back is scary! mopwer06-11-2007, 08:12 AMOr a new head...

True... PETC06-11-2007, 12:41 PMI won't do it too close, or do it if they don't have full size rock guards. RickyB06-11-2007, 02:01 PMI watched part of that show and it struck me as odd that the concept of drafting would be treated as "myth" when it is built on very solid principles of physics and applied in many real-life situations.

Anybody who has done any bicycle racing or has watched pro bike road racing understands the concept of drafting and why the race always has a main group (the "peleton") which is basically a bunch of riders taking turns at the front where they expend maximum effort fighting air resistance and then taking time inside the group where they can cruise along at the same speed while expending substantially less energy. The peleton has physics on its side and a group of riders who work together in this fashion taking turns at the front can always catch a lone rider or a small group of riders who try to break away from the pack too far from the finish.

The same is true of migrating birds who make V formations. The lead bird works hardest and the rest go at the same speed expending less effort. Similar formations were used by bomber squadrons in WW2 to conserve fuel and extend their range. The smaller fighter escorts in particular would ride just behind the bomber's wings saving their precious fuel for their defensive role.

Drafting is very common in car racing where a car can use a leading car to build up speed and slingshot itself past the leading car.

What was interesting about the testing they did was that even at safe following distances of 75-100ft that as much as a 20% improvement can be expected. The only time I have done this is when I was moving and I drove behind the moving truck we rented to haul my furniture. Even though I followed the truck at a safe distance, I constantly stayed behind it for nearly 400 miles and I got the best highway mileage on that trip that I ever managed to get out of the car I had at the time.

If you don't mind the extra rock chips and the slower uphill speeds, following a truck at the safe distance is a great way to stretch your fuel tank. Just use the old trick of waiting for the back of the truck to clear a mark on the road and then have time to count one-thousand-one, one-thousand-two before your front end reaches the same mark. Gairloch06-11-2007, 02:18 PMYa, that sounds pretty good. Not necessarly zero air, but substantially less.

I wonder if the radiator will get enough air flow for extended amounts of time of doing this though.

I'm pretty sure it's not less air or we'd be hearing all kinds of warnings about don't draft on highways with the family wagon or your babies will die of SIDs or something like that. It's that the air is disturbed and easier to move through. Hellstorm06-11-2007, 03:09 PMHahahaha.... thats funny...i thought i was the only idiot out there that drafted behind semi's. Im a contract mechanic for UPS and i get sent all over east Tx to work at different centers. Sometimes i have to drive about 5 hours....so i find a good big Truck....set the cruise control to his speed and get up about 15ft from the back of him......sometimes they dont even know ur there....and other times they get pissed and keep switching lanes to get you from behind them. mopwer06-11-2007, 03:13 PMI watched part of that show and it struck me as odd that the concept of drafting would be treated as "myth" when it is built on very solid principles of physics and applied in many real-life situations.

They're running out of real Myths...

Greg mr2man06-11-2007, 03:52 PMInteresting TheAmazingDave06-11-2007, 04:46 PMThey're running out of real Myths...

Greg

They didn't test the concept of drafting as the myth. What they tested was if drafting could yeild substantial fuel savings. Bak@EMSPowered06-11-2007, 06:14 PMrock chips! PETC06-11-2007, 06:43 PMNot if you stay back! lol

I've never gotten one. Just don't follow trucks without mudflaps. Bak@EMSPowered06-11-2007, 06:45 PMand dont try drafting... PETC06-11-2007, 07:01 PMWhy? It saves a ton of gas. I can get 38 MPG while drafting. Bak@EMSPowered06-11-2007, 07:24 PMWhy? It saves a ton of gas. I can get 38 MPG while drafting.

* rock chips
* not safe traveling distance
* truck driver cant see you
.....

do i need to go on about why? PETC06-11-2007, 07:50 PMYou don't get rock chips, 100 feet is PLENTY safe really... and as long as you can see his mirors he can see you. lol 3133706-13-2007, 10:31 AMHere in Northern Virginia there is too much traffic to draft. TomsMR206-19-2007, 11:40 PMif you cant SEVERELY outbrake a fullsize semi truck, your car has serious detrimental problems that need to be fixed ;) the most dangerous part about it is probably the rock chips.. mr2slow4you06-20-2007, 06:22 AM^This is why I have always wondered why semis are always tail gating other regular sized cars. They are such ***** because they must know if something occurred ahead of them, and that car in front had to brake they would basically screw over some people. It frustrates me that they take an assumed accepted risk for everyone. David06-21-2007, 12:21 PMDid anyone watch the part with the firebird entering the semi? I thought as soon as the rear wheels got on, it would fly like a bird to the inside of the truck, and cause some serious fire.:rofl::rofl::rofl::rofl::rofl::rofl: slo-two06-21-2007, 02:19 PMDidn't those Mythbusters use a minivan to test the drafting theory? With the aerodynamic grace of a somewhat smoothed brick? One would expect that drafting would do less good for a 2 because of our somewhat lower coefficient of drag and much smaller frontal area. On the other hand, drafting should be very effective for an xB or an Element or some other vehicle modeled after a cinderblock.

Is 38 MPG really much savings? My 91T gets about 34 on highways when not drafting, as long as I don't have the wide wheels on it. And having to buy a new windshield every 10K miles (due to rock chips, sandblasting, etc.) would be such a pain... David06-21-2007, 02:23 PMjust keep a distance. phzoinkMKII06-21-2007, 03:18 PMDidn't those Mythbusters use a minivan to test the drafting theory? With the aerodynamic grace of a somewhat smoothed brick? One would expect that drafting would do less good for a 2 because of our somewhat lower coefficient of drag and much smaller frontal area. On the other hand, drafting should be very effective for an xB or an Element or some other vehicle modeled after a cinderblock.

Is 38 MPG really much savings? My 91T gets about 34 on highways when not drafting, as long as I don't have the wide wheels on it. And having to buy a new windshield every 10K miles (due to rock chips, sandblasting, etc.) would be such a pain...

Dodge magnum mr2slow4you06-21-2007, 06:17 PMDidn't those Mythbusters use a minivan to test the drafting theory? With the aerodynamic grace of a somewhat smoothed brick? One would expect that drafting would do less good for a 2 because of our somewhat lower coefficient of drag and much smaller frontal area. On the other hand, drafting should be very effective for an xB or an Element or some other vehicle modeled after a cinderblock.

Is 38 MPG really much savings? My 91T gets about 34 on highways when not drafting, as long as I don't have the wide wheels on it. And having to buy a new windshield every 10K miles (due to rock chips, sandblasting, etc.) would be such a pain...

Do you have ems/tunning/larger turbo to achieve 34mpg? Gairloch06-21-2007, 06:19 PM^ He has an NA I'm sure. I've gotten 34 mpg with mine before. mr2slow4you06-22-2007, 01:37 AM^He said 91T unless it was a typo. BMK06-25-2007, 09:30 AMDrafting is great for long distances, but short distances i get annoyed cuz the trucks drive so slow. Sylvan09-01-2007, 05:57 PMThis reminds me of that movie, Breaking Away, where that kid is on his bicycle and he drafts a semi for a few minutes, up to 60 mph, and then he passes it! lol. Then the semi gets pulled over for speeding, haha. David09-01-2007, 06:06 PMwow, i thought this thread was dead Dance_Business09-01-2007, 09:52 PMRobbie Benton in that movie? Been a long time. Ryansmagic09-04-2007, 04:29 PMTruck drivers HATE THIS! They can't see you, so when they are going to change lanes and they look back, nothing is there, then 5 seconds later you switch lanes to pass, you just apear there to them! bad situation.... fosley09-06-2007, 05:56 PMOk, as long as you have enough distance for reaction time, you shouldn't have any trouble out-braking a semi. Seriously, what has a longer stopping distance besides a train? Next, since you're behind the semi, it doesn't matter if he changes lanes because you aren't there for him to hit. Or, to say it differently, if a semi driver *tried* to hit you, you'd have to be paying no attention for it to work.

Note that this works for things besides semi's also; my friend and I tag-teamed a trip back from Albequerque, NM to Tucson, AZ with a Fiero/MR2 combo and got 10-15% better gas mileage. You have to switch out every 30 minutes or so to even out the savings so both tanks deplete about equally, but this is a good thing since it makes the trip less tiresome since you alternate between pacing and navigating.

However, something to note: air resistance plays a big role in stopping from high speeds. If you are drafting and try to stop at 80 mph, it will be harder than stopping from 80 mph in open air because you are lacking the aid of air resistance. Not enough that a semi will out-brake you, but enough to catch you off-guard. Normally, I slow down by letting off the accelerator and very rarely need my brakes on the highway. Drafting the Fiero though, I also had to move to one side or the other to catch some wind, or he would engine brake much faster than me, requiring the use of my brakes. 20incher09-10-2007, 07:09 AMThis is the same technique nascar has been using for years, they stay in 2nd and let the winner use up alot more gas then they are going to have to. Then at the end pull ahead and take the race. On a sidenote i just have a problem with having a vehicle in front of me...just annoys me. *shrugs* breadbooze09-12-2007, 04:52 PMTrying to justify unsafe driving practices for the sake of saving gas is pretty lame, for lack of a better term. Surely a MR2 can stop quicker than a semi, but you will lose the big picture; what's happening on the road ahead of the semi. You also take away an out; the space cushion ahead of you is the ONLY out you have control over. Bak@EMSPowered09-12-2007, 07:03 PMTrying to justify unsafe driving practices for the sake of saving gas is pretty lame, for lack of a better term. Surely a MR2 can stop quicker than a semi, but you will lose the big picture; what's happening on the road ahead of the semi. You also take away an out; the space cushion ahead of you is the ONLY out you have control over.

Logic won't work with these folks... just wait, there'll be more replies to your post about how its super safe and doesnt harm anyone... ;) :devil: fosley09-12-2007, 07:57 PMSurely a MR2 can stop quicker than a semi, but you will lose the big picture; what's happening on the road ahead of the semi.Ok, but you have to stay *way* back to really see anything of use around a semi, so "normal" driving won't help that aspect much, if any.

[flamesuit]In this case you're saying "To be sure, an MR2. . .", which is shortened to "Sure, an MR2. . .", rather than "surely". And since I'm here, it's "An em-are-two", not "A em-are-two". :zipit:

the space cushion ahead of you is the ONLY out you have control over.Not if you have a built-in ejection seat. Sheesh! :omg:

This is a problem if there's another semi right behind you, but it's not really a problem normally. Whatever's in the road up there will get creamed by the semi (and therefore give you plenty of room to stop), and if he dodges it, you only need 3-4 semi-lengths to come to a complete stop, or you can just follow him over, or probably just brake hard and drive onto the shoulder, or go around on the center line.

We'd need to do some research, but the question becomes: does the increase in accident probability from following "too closely" outweigh the decrease in accident probability from not exiting/entering the freeway as often? I really wouldn't think so, but like I said, we'd have to do some research to be sure.

Edit: The other fallacy I see very often is that it's more dangerous to tailgate a semi than a car, which I say is untrue. If you are X distance from both, you're more likely to rear-end the car if he tries to stop (he stops faster), you probably won't have as much warning between the time he swerves and you realize there's something in the way, and the time you hit or miss it (the semi gives you a guaranteed 50-60 feet + follow distance, while the car gives you 15-20 feet tops, plus the car is more likely to wait until the last second to swerve, plus the semi is more likely to see it coming to begin with and just slow down), and if the semi hits something, he's more likely to push through and give you a path, while the car is more likely to come to a very rapid stop in your face. breadbooze09-12-2007, 09:21 PMOk, but you have to stay *way* back to really see anything of use around a semi, so "normal" driving won't help that aspect much, if any.

Which is EXACTLY what you should be doing to begin with. 4-6 seconds under 30mph, 6-8 over 30. Very conservative, but years of driving UPS semi's have it drilled to my head.


[flamesuit]In this case you're saying "To be sure, an MR2. . .", which is shortened to "Sure, an MR2. . .", rather than "surely". And since I'm here, it's "An em-are-two", not "A em-are-two". :zipit:

Cool. Though I was taught you use "an" when preceeding a vowel. That was in 2nd grade, it's been a while.


Not if you have a built-in ejection seat. Sheesh! :omg:

This is a problem if there's another semi right behind you, but it's not really a problem normally. Whatever's in the road up there will get creamed by the semi (and therefore give you plenty of room to stop), and if he dodges it, you only need 3-4 semi-lengths to come to a complete stop, or you can just follow him over, or probably just brake hard and drive onto the shoulder, or go around on the center line.

We'd need to do some research, but the question becomes: does the increase in accident probability from following "too closely" outweigh the decrease in accident probability from not exiting/entering the freeway as often? I really wouldn't think so, but like I said, we'd have to do some research to be sure.

Edit: The other fallacy I see very often is that it's more dangerous to tailgate a semi than a car, which I say is untrue. If you are X distance from both, you're more likely to rear-end the car if he tries to stop (he stops faster), you probably won't have as much warning between the time he swerves and you realize there's something in the way, and the time you hit or miss it (the semi gives you a guaranteed 50-60 feet + follow distance, while the car gives you 15-20 feet tops, plus the car is more likely to wait until the last second to swerve, plus the semi is more likely to see it coming to begin with and just slow down), and if the semi hits something, he's more likely to push through and give you a path, while the car is more likely to come to a very rapid stop in your face.

Accidents don't "normally" happen either. Better to avoid the abnormal than to assume things are always normal.

Trying to justify unsafe driving practices by quoting physics formulaes and drawing up ambiguous figures to support them is lame at best, for lack of a better term.

Have you plowed into a deer that a semi ran over? fosley09-13-2007, 01:02 PM4-6 seconds under 30mph, 6-8 over 30.Well, I think that's overkill (unless you are driving a big truck or something), but I won't argue that it isn't safer than being 3 car lengths back at 70 mph. I normally drive about 1 second back in-town and 2 seconds back on the highway. I also back off when I'm not in a sports car with good brakes (a rare occurrence). My problem with 6-8 seconds is that by the time I can determine how rapidly they're braking, I'm 3-4 seconds away, but have to do a lot more stopping because they got a few second headstart on me.

Cool. Though I was taught you use "an" when preceeding a vowel.The difference is that "MR2" is an acronym and pronounced "em-are-two", not "mur-two". "An" for a, e, f, h, i, l, m, n, o, r, s, u, x; "a" for b, c, d, g, j, k, p, q, t, v, w, y, z.

Accidents don't "normally" happen either. Better to avoid the abnormal than to assume things are always normal.What I meant is that you have to pay attention to what's behind you. If a car comes up behind you, back off a bit, and if a semi is following you, obviously you want an even bigger forward buffer. But most of the time, where I drive anyway, there's nothing behind me to worry about.

Have you plowed into a deer that a semi ran over?I've plowed through the debris field of a Porcshe that a semi ran over, but no deer. I don't really see deer being a problem though. First, the semi will probably hit his brakes to avoid the deer, so you'll already know something is up. Second, when he hits it, even if it goes straight under the semi, it will get accelerated to high-ish speeds, so when you see it coming at you under the semi, you won't be doing a 25 foot panic stop from 70 mph, but more of a 100-200 foot panic stop from 60 mph. Third, most of the deer I've seen get hit by a semi went to one side or the other. Fourth, it will be a lot more dead if a semi hits it first, and less likely to kick you to death through the windshield. Fifth, hopefully it'll be on the ground by that time and you'll strike its body with your bumper, rather than taking out its legs and having the body come through the windshield into your lap. Given the amount of crap a deer would have to go through to get to your car, I'd say you're probably safer from deer while following the semi than not. Especially if the likelyhood of a deer strike is high. Not necessarily less likely to hit it, but safer.

But in my experience, you're far safer tailgating a semi than you are passing it. I've been forced to drive off the road and/or stomp on the brakes to avoid getting hit by a swerving/sliding semi more times in the past 2 years alone than I've ever had problems with tailgating one. So while it may be more dangerous than following way back, it's not really that dangerous in the grand scheme of things. breadbooze09-13-2007, 02:29 PMIt's all fun and games until the shit hits the fan.

I'll thank you for raising my insurance premiums at a future time. Bak@EMSPowered09-13-2007, 03:55 PM^^ Yup JMcDonald09-13-2007, 04:30 PMI do think it could be more dangerous (although, as Fosely pointed out, it seems you are a little bit safer than hitting a deer on your own, or swirving to miss it and hitting a tree) than following at a safer distance. However I am quite interested in trying out the tag-team thing next time Im on a road trip with friends. Although Id have to be in front the whole to for it to reotely even out, since they all drive 18 MPG Supras :p . MR2SW2209-27-2007, 05:21 PMi was about 4-5 car lenghts behind a semi for 150 miles on the way back to cali a week ago, it was producing 28-29 mpg on my 91t, it's got an intake 2.5dp so it's basically stock, then again my motor's 1st cylinder is low on compression so i bet if the engine was working better then i might have gotten over 30mpg. but as people were saying it's not the safest thing to do, when they would change lanes, i would drop back a couple more car lengths to let them see i was there but i wouldn't ever try 20-30 feet, thats just crazy:wtf:. Bak@EMSPowered09-27-2007, 06:26 PMi was about 4-5 car lenghts behind a semi for 150 miles on the way back to cali a week ago, it was producing 28-29 mpg on my 91t, it's got an intake 2.5dp so it's basically stock, then again my motor's 1st cylinder is low on compression so i bet if the engine was working better then i might have gotten over 30mpg. but as people were saying it's not the safest thing to do, when they would change lanes, i would drop back a couple more car lengths to let them see i was there but i wouldn't ever try 20-30 feet, thats just crazy:wtf:.

Isn't that pretty normal MPG for an MR2 on the highway? MR2SW2209-27-2007, 06:30 PMIsn't that pretty normal MPG for an MR2 on the highway?

i just found out 2 days ago i have had #1 cylinder is busted, 90psi compression on that cyl, and 151-152 on the other 3, and i consumed 2-3 quarts of oil in 250 miles of the 350 trip. and yes, 28 mpg is normal for a normal operating 3sgte. 3sgtepower09-27-2007, 09:48 PMAs nice a fuel economy percentages those are, I would never draft in a car I cared about. I was once riding with this eclipse gs ricer that had put on a $3000 turbokit to his 420gay. He was real proud of his 175whp beast and showing it off to me.

He got right behind a dumptruck, and I said I wouldnt hang behind it cuz it might hit your windsheild with a rock, and then he talked about how drafting large trucks saves so much money in gas. Then the dump truck let out a bunch of fist sized rocks, and a couple of them punched larged holes into his FMIC :lol:

I didn't wanna say "I told ya" cuz he was pissed, but lesson learned. JMcDonald10-01-2007, 01:59 AMAs nice a fuel economy percentages those are, I would never draft in a car I cared about. I was once riding with this eclipse gs ricer that had put on a $3000 turbokit to his 420gay. He was real proud of his 175whp beast and showing it off to me.

He got right behind a dumptruck, and I said I wouldnt hang behind it cuz it might hit your windsheild with a rock, and then he talked about how drafting large trucks saves so much money in gas. Then the dump truck let out a bunch of fist sized rocks, and a couple of them punched larged holes into his FMIC :lol:

I didn't wanna say "I told ya" cuz he was pissed, but lesson learned.

Heh, I probably wouldnt draft semis either. But I am still curious about doing it with another friend in a car.

BTW, I got 30 MPG in a stock MR2 going to NA2005. Did quite a bit of boosting, and had the AC on. MR2SW2210-01-2007, 10:50 AMHeh, I probably wouldnt draft semis either. But I am still curious about doing it with another friend in a car.

BTW, I got 30 MPG in a stock MR2 going to NA2005. Did quite a bit of boosting, and had the AC on.

makes me think that i could have bee around 30mpg if i had proper compression:rolleyes: fosley10-02-2007, 10:39 AMHere's me drafting a semi:
http://www.tmobilepictures.com/photo/photo26/d6/04/e050377ce894.jpg (http://www.tmobilepictures.com/photo/photo26/d6/04/e050377ce894.jpg?tw=305&th=228&_rh=2k89pzl197pg7chxnibnk4t74)

Unfortunately I got no benefits, as we were driving at a lower speed than my speedo registers for 10+ miles. Stupid construction zones. :(

http://www.tmobilepictures.com/photo/photo29/fe/b0/53b755f7884a.jpg (http://www.tmobilepictures.com/photo/photo29/fe/b0/53b755f7884a.jpg?tw=305&th=228&_rh=evq6pggkzbl2gcmtxb053degr) http://www.tmobilepictures.com/photo/photo15/97/37/5f62679b5712.jpg (http://www.tmobilepictures.com/photo/photo15/97/37/5f62679b5712.jpg?tw=305&th=228&_rh=avvzkmlfd8xmk3uonnfgl5mx8) http://www.tmobilepictures.com/photo/photo14/84/cb/63cd6d04b310.jpg (http://www.tmobilepictures.com/photo/photo14/84/cb/63cd6d04b310.jpg?tw=305&th=228&_rh=2mgnq6rcgm6lu2gsd5xaszhu0) Roger_Rabbit10-07-2007, 01:56 AMI drafted earlier today... I pulled between the draftee (truck in front that I am drafting off of) and the drafter (another truck that was about 35 foot behind the draftee)... It was fun till I had to exit... Bak@EMSPowered10-07-2007, 04:29 PMI drafted earlier today... I pulled between the draftee (truck in front that I am drafting off of) and the drafter (another truck that was about 35 foot behind the draftee)... It was fun till I had to exit...

real smart. ixtlann11-18-2007, 09:40 AMThis is one way to look at it, or another way to look at is that a car like an mar2 or del sol can achieve similar results or maximum results by following a lesser truck, ie were smaller etc so we can get the result by jut hangin behind a jeep cherokee or minivan etc. i tried this on my honda del sol (mr2 ish shaped) a few years ago it was ridiculous 48+ mpg i dont have a non draftin trip to compare it to though but thats obviously better then stock fuel economy.


Didn't those Mythbusters use a minivan to test the drafting theory? With the aerodynamic grace of a somewhat smoothed brick? One would expect that drafting would do less good for a 2 because of our somewhat lower coefficient of drag and much smaller frontal area. On the other hand, drafting should be very effective for an xB or an Element or some other vehicle modeled after a cinderblock.

Is 38 MPG really much savings? My 91T gets about 34 on highways when not drafting, as long as I don't have the wide wheels on it. And having to buy a new windshield every 10K miles (due to rock chips, sandblasting, etc.) would be such a pain... mr2-bob11-25-2007, 01:06 AMI like the drafting with a buddy idea...at least you know he won't be pissed if you are on his bumper.

Back when I had a 1972 Honda CB450, I would only get 150 miles on a tank of gas...unless I drafted. I would ask permission from the trucker to draft, and most would say yes. It was very difficult to stay stable back there because of the eddies (turbulence) comming off from the back, but I would get over 200 miles on that same tank of gas if I stayed in the draft.

The eddies that come off from a truck moving above 65 mph are so strong that they literally will suck the car along when in the eddy if you get close enough. Moving Van semi's do this the best because their trailers are closer to the ground. (and you can test this in a swimming pool with two people. I've "towed" my daughter across the pool just by using the "draft" of my body once I got us both moving. I would take my hands away and she would stay right with me as long as I moved quickly through the water.)

Now, if you really pay attention to drafting in NASCAR, you will realize that several cars drafting in a line together use less fuel and go faster than a "train" of fewer cars drafting. Again, it has to do with air flow around a "body". Longer "bodies" create less drag than shorter bodies, even if both have the same cross section.

Engineering is fun.:D ARZ12-11-2007, 11:32 PMYou can all call BS but, I personally have drafted many a Semi and delivery vans when I raced my bike (Bicycle) in high school and College, more than a dozen times I have seen over 60 mph on my bicycle computer. My personal best was 67mph. My personal best not drafting is 55mph (just a huge hill and a tailwind).

When we were going on certain rides I would change my big ring to a 55 tooth and adjust my front dérailleur and pay attention not to get to a bigger cog on the rear, when going slow. Hardest thing was this was back before lever shifters, my shifters were on the down tube. In the 40-50 mph range was easy as pie, it was just hard to find a Semi going that speed and to catch them at that magic acceleration speed. If they were heavily loaded or we caught them on a roll we might be able to stick with them thru that magical 30-45 mph range.

For some reason if you didnt have something like a strong tailwind or a hill that helped get you up to 35 MPH then we would almost always be too spent to maintain and gain speed and inevitably loose the draft. If the terrain stayed level and the road was smooth and the driver was steady it was surprisingly easy to go 55 mph for quite a while. When we were done we would always pull out so the driver could see us and we would yahoo and if the drivers saw us they would always give us the thumbs up.

GOOD TIMES!!!! trdny12-14-2007, 12:14 AMARZ: many good riders can get up to those speeds without the hill or tailwinds. pure leg power. fosley12-17-2007, 10:30 AMLast time I did the math, at 50 mph the difference between 0 power and that Armstrong guy at peak power was about a 2 mph difference. That's assuming you're using a hill to get to 50 mph, so if you aren't, adding that difference (around 500 watts, as I recall) would get you the 2 mph--though that would mean you're putting out way more power than Armstrong, which isn't something I would require to be considered a "good rider".

Of course, the design of the bike makes a difference--they've gotten pedal-powered vehicles to over 200 mph--but I don't think 65 mph is normally acheivable without either a draft or a hill. According to my calculations, the fast road bikes where your body is horizontal (minimizing wind resistance) can get to just under 70 mph on an 18% grade, or just over 70 mph if you add in the 500 watts, but 18% is *steep*. Mr2civic81712-17-2007, 12:34 PMI rather Spend 40$ a tank, then risk my life or my 2 then, Drafting behind an 18 wheeler, to save gas. Mr2civic81712-17-2007, 12:35 PMI rather Spend 40$ a tank, then risk my life or my 2 then, Drafting behind an 18 wheeler, to save gas. Recklesss02-06-2008, 06:05 PMI was driving around in a 1986 Toyota 4x4 for a while. Great truck, but she was a 4 banger, and she maxed out around 55-65 mph (depending on which way the wind was blowing)

however, if i drafted up behind a big rig (it worked from a good 4 or 5 carlengths too) i could zip up to around 85 before i had to pass the truck...

then id hit another wall of air, but it still worked:D LokiRx702-09-2008, 09:35 AMI love how everyone condemns drafting. And yet unless you live in boon country you drive in traffic. I live in Ohio, and people regularly ride my ass anywhere from 15 feet to three feet away. This is when I am doing the speed limit, and they want to do 80 or 90. I can safely say that I regularly drive close to 50 feet or even less to the car in front of me. Do I have a choice? Not really, rush hour doesnt give you many options, people are all around you.

Truck drivers 9/10 times are superior drivers to 90% of the idiots I encounter on the road in a day. I feel much safer behind a Semi than I do the average person in traffic that taps the brakes every .025 seconds... On rare occasion a semi may change lanes to seemingly get away from me, if he does, I move on to another trucker. I work at UPS and alot of the truck drivers I talk to, dont really mind as long as they can see you (I.E you can see their mirrors)

If you really feel the need to talk about how dangerous drafting is, thats nice. Most of the people raising your premiums most likely dont even visit car forums, much less know what drafting is. Why dont you go to a street racing forum and preach there, I am not endangering anyone but myself, I seriously doubt the truck driver is getting injured in any way. And if anyone behind me gets involved they were following too closely. And on the subject of deer, do you know what happens when a semi hits a deer? It isnt often that the deer goes under the truck, usually there isnt much deer left over.

Anyway, figured I would put this to bed. I mean really, there are more people that tailgate other motorists than semis. If you feel the need to bash drafting go look up the soccer mom forums and give them a piece of your mind.

And FYI I dont draft regularly. I do it on long trips, but I dont take those that often. For the most part I get stuck, with little to no choice, in bumper to bumper 80 mph traffic. scooterman02-09-2008, 10:03 AMdoing 70+ mph on a 18% grade on a bicycle is crazy. Your tires aren't wide enough to stop you, it would probably take several hundred meters to stop.
also 18% is very very very steep, there are a few hills around here that peak at 18-22%, it sucks ball riding up them, and there is one i will not ride a road bike down (24%) (mossy and wet, with a 180* corner at the end).

The fastest ive hit on my bike downhill is the mid 50's due to fear and not enough hill left. Fastest on a flat just under 40 w/o drafting. I've never had the opportunity to draft a truck on the road when on my road bike.

Now drafting i hit 44 on my mountain bike!!! behind a dump trunk, on this one road i road to work on. I didn't even notice how fast i was going i was just looking at the truck, i was at the end of the road in no time and looked down at the computer.

I wouldn't mind so much if someone was drafting me not like its worth drafting an mr2 anyway. But i wish we had some type of light on the car that signaled, hey i dont want to pass you im just gonna hang out back here and draft you.

I dont draft around here people will heavily apply the brakes for no reason other than they look down at the speedo and see omg im doing 80 slam on the brakes. killerkid0806-23-2010, 09:52 PMlol, thread revival,

scared to draft a semi, draft a car.

3 hours - half a tank - 90 mph

BAM ! LeePeyton06-24-2010, 12:27 AMUnholy Undead thread Batman....... I'm gonna go get my gun and aim for the brains. Powered by vBulletin® Version 4.2.5 Copyright © 2026 vBulletin Solutions Inc. All rights reserved.