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Discussion Starter #1
...so I'm watching Mythbusters and they're doing a section on "drafting" a semi truck. Long story short...they started at 100' and worked up to less than a foot from the trailer. The technique works execptionally well. The show got about 40% better fuel economy.

so

During our drive to Orlando from Atlanta recently, I decided to try it for myself. I selected "avg/mpg" and hit reset while I was steady at 75mph on my own...no drafting. Got a whopping 15-16 mpg. ugh. Then I found a semi moving at a pretty good speed, got behind him and set the cruise control. Hit reset again and after a while, I was getting 19.7-20/mpg! I was about 4-6 car lengths behind. The problems are this, you gotta constanly hit "accel" or "de-accel" on the steering wheel to tweak your speed to match his...each button press is 1/mph of change. Hills don't help things...those trucks don't maintain speed too well on ups and downs. But it gives you something to do on the drive.

The other problem is finding an 18wheeler that isn't going 55-60. I just can't purposely go THAT slow while everyone else is whipping by at 75-85.

Thought I'd pass this along to you guys...
 

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I saw that episode a few months ago. You have to drive insanely close (tailgating) to realize signficant gains, which is probably a really bad idea unless you have a death wish!

Seriously, why risk it to save a few MPGs?
 

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4-6 car lengths, I wouldn't consider a "death wish".

That's a pretty good improvement you got, Hemi! The highways around here are FULL of semi's that seem to always break the speed limiits, so finding one going faster than 55-60 is no problem at all. Thanks for the info.
 

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I agree that this is a great idea for a long drive to save money. Semitrucks have a much longer stopping distance than any XK on the road, even if they lock up the brakes at highway speed 4-6 car lenghts should be safe. Keep in mind another Mythbusters I saw where they tested the effects of a semitrailer tire when it explodes. The myth was based on a trailer tire being fatel for a motorcycle. They also proved it could go through a car window and decapitate you! I would make sure the trailer you are following looks pretty new.
 

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I agree, and being that close to a semi is dangerous.

BTW, where in CR are you turbo?
 

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Truck drivers hate this. If you draft behind them for a while they will start swerving back and forth to shake you off. Personally, when driving a long distance I prefer to look at scenery other than the back end of an eighteen wheeler. I also like to see well in front for safety reasons.

4-5mpg increase is not going to affect my lifestyle but an accident might.
 

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Discussion Starter #9
I'm not so close that it should bother them. They draft each other at similar distances or even close..I've seen. On a 500 mile drive, 5mpgs can make a difference. And those of you worried about fod from the road...rocks can/will bounce whether you're at 4 car lenths or 14 at highway speeds...even from a car. Just don't draft a dump truck.
 

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I try to avoid large trucks when I'm driving. Too much to go wrong with debris, blown tires and the like, plus many modern drivers aren't very good. Not the same professionals that used to drive 20-30 years ago. ..
I'm just wondering when we'll see some yahoo figure out a way to attach their car to the back bumper of a semi-trailer.. Imagine a tow bar with some sort of remotely controlled coupler that could grab the bumper.. Kinda like those remote control arms on submarines..
I don't think it would be all that hard to do, the technology wouldn't be any more sophisticated than what's used on snowplows.
One could just hook up to a trailer and let go of the wheel.. Plus get really outrageous mileage..
I sure wouldn't want to be attached to the trailer like that though..
 

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sciron4x4 said:
4-6 car lengths, I wouldn't consider a "death wish".

That's a pretty good improvement you got, Hemi! The highways around here are FULL of semi's that seem to always break the speed limiits, so finding one going faster than 55-60 is no problem at all. Thanks for the info.

Did you see the episode? According to Myth Busters, you have to be VERY close to realize the best gains. I believe they recorded improvements each step of experiment until they were literally on the bumper of the big rig. Only then did they not realize a gain. Four to six car lenghts with no visibility ahead of you at highway speeds is asking for trouble, IMO.

At 60 mph, you're travelling 88 feet per second. If your vehicle is 15 feet long and you are four lenghts behind the semi, well....you can do the math and see where I'm going with this. Personally, if I were that worried about a few MPG, I'd buy a more economical vehicle rather than put myself and my family in danger by tailgating a semi. And I'm sure that just about any cop would pull over a motorist for following too closely at those kind of distances/speeds.
 

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TR4Runner...I agree and lets not forget all the debris being thrown from the roadway and into your vehicle by 18 wheels. Never mind the occasional tire treads. I'd rather buy the fuel.
 

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Commander Ron said:
TR4Runner...I agree and lets not forget all the debris being thrown from the roadway and into your vehicle by 18 wheels. Never mind the occasional tire treads. I'd rather buy the fuel.
Good point. It's an interesting discussion though...

I wonder if three or four vehicles of similar size/dimensions would realize a similar increase in MPG if they were drafting each other NASCAR style? I'm sure that would be just as risky, but I don't see why it wouldn't work.
 

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Discussion Starter #16
given the amount of traffic when I was driving, I was no closer to him than any other pair of cars/trucks that day. I wasn't driving so close that the highway patrol would pull me over. Six car lengths may have been inaccurate...but about 100ish feet or so.

:p My next trick is inspired from a previous post. I will mount a makeshift harness to the front of the Commander's frame. It will retract beneath when not in use...on the end will be a pair of electro magnets powered from vehicle's electrical system...a larger altenator will be installed. When I pull up to a semi at on the interstate, the harness will extend and attatch to that low protection bar on the end of the trailers with the magnets...put her in nuetral and enjoy the ride watching a movie since I'll install the "lockpick" for my nav/dvd. :rolleyes:
 

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jeep5253 said:
Speaking of Mythbusters, here's one of my favorite youtube vids ( I have a crush on Kari): http://www.youtube.com/watch?v=OxaPpbJv1fk
I agree with you, Kari is a smokin hottie. I also like the girl from Extreme 4x4, she is hot and she builds jeeps. (sorry for getting off topic)
 

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Discussion Starter #20
Did another FL road trip this weekend. Drafted again.

...remembering this thread while on the road, I definately wasn't in a dangerous position. I hooked up with a large U-haul that was "hauling a s s" too...that worked as well. At the distance I was at...averaging 100' or so, I'd gain about 4mpgs. It would settle down around 19mpg at 75 when drafting.
 
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