| ShaggyUSM |
According to Mythbusters, you get DRAMATICALLY better gas mileage by driving behind (drafting) an 18 wheeler. Benefits begin at 100 ft, and steadily improve as you get closer. Drafting works! I confirmed this in the Murano using the fuel economy bar graph thingy. When NOT behind the 18 wheeler at 70 mph, the graph was somewhere between 23 and 27 mpg (depending on hills etc). Then I pulled behind a semi doing the SAME speed (70 mph) as I was before and the gauge shot up and pegged out at 30 mpg. So since it won't go above 30 on the bar graph thing, I don't know just how much I was doing because I didn't want to reset the "average mpg". This was at about 50 feet behind a semi. IT WORKS! Not just plausible, it really works!
:2: :2: :2: :2: :2: :2: :2: :2:
The test vehicle was a Dodge Magnum (v6?)
55mph control: 32mpg
100ft: 35.5mpg, 11% improvement
50ft: 38.5mpg, 20%
20ft: 40.5mpg, 27%
10ft: 44.5mpg, 39%
2ft: 41mpg, 29% |
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| Kris |
I never doubted it. This is what Nascar drivers do, bike riders etc. And there is a simple explanation to it - less drag!
However, not everything is rosy here - think safety! |
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| njjoe |
Hmmm... they also did a test where they dropped a toaster into a bathtub. Do you want to verify those results also? :2:
-njjoe |
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| Kris |
quote:
Originally posted by njjoe
Hmmm... they also did a test where they dropped a toaster into a bathtub. Do you want to verify those results also? :2:
-njjoe
That would be easy Joe ;)
of course the toaster would have to be unplugged....:2: |
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| ShaggyUSM |
Well, I wasn't saying to be dangerous about it. I definitely wouldn't get any closer than 50 - 100 ft. But I KNOW I'm doing it on any long road trips in the future for SURE! And yeah, it's all about drag. Here is a link to the experiment's details:
http://kwc.org/mythbusters/2007/06/..._rig_myths.html |
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| Corin |
Might I recommend NOT pissing off the truckers. They don't like you getting close because then they can't see you. Plus, you can't see what's going on ahead of you at all.
When a semi has an empty load, those suckers can stop REALLY quickly. And if you're not paying really close attention, you'd be in big trouble, particularly with respect to where their truck is going to collide with your vehicle (think windshield).
When I had my old '81 diesel rabbit, I had one of those emergency CB radios. Going over the pass, that stupid little car had a really tough time keeping up speed. If I found a semi going about the right speed, I'd radio to them and ask permission to draft them just so I could keep up my speed (yeah, I know, my car couldn't even keep up with a semi going up the pass unless I was drafting). They usually didn't mind, in fact they thought it was funny, but they really appreciated knowing that I was doing it intentionally and asking permission, so then they watched out for me a bit (like making sure they didn't do sudden stops).
Drafting, I could leave it in 4th gear and go about 55mph all the way up the pass (assuming I could find a truck going that speed). Without, I was shifting between 4th and 3rd constantly, doing 40-45mph.
HOWEVER, I would NEVER get to close to the back of a semi without making SURE that they knew I was back there and that they were OK with it. Since I don't have a CB in my MO, and because I generally want to go faster than the semis, I don't draft anymore.
(oh, and as for MPG, I didn't really notice a different in the rabbit. It already got over 40mpg, and diesel was cheap at the time, so I didn't really pay attention to it. I just cared about the speed...) ;) |
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| Lightninrod |
quote:
Originally posted by Corin
Might I recommend NOT pissing off the truckers. They don't like you getting close because then they can't see you. Plus, you can't see what's going on ahead of you at all.
When a semi has an empty load, those suckers can stop REALLY quickly. And if you're not paying really close attention, you'd be in big trouble, particularly with respect to where their truck is going to collide with your vehicle (think windshield).
When I had my old '81 diesel rabbit, I had one of those emergency CB radios. Going over the pass, that stupid little car had a really tough time keeping up speed. If I found a semi going about the right speed, I'd radio to them and ask permission to draft them just so I could keep up my speed (yeah, I know, my car couldn't even keep up with a semi going up the pass unless I was drafting). They usually didn't mind, in fact they thought it was funny, but they really appreciated knowing that I was doing it intentionally and asking permission, so then they watched out for me a bit (like making sure they didn't do sudden stops).
Drafting, I could leave it in 4th gear and go about 55mph all the way up the pass (assuming I could find a truck going that speed). Without, I was shifting between 4th and 3rd constantly, doing 40-45mph.
HOWEVER, I would NEVER get to close to the back of a semi without making SURE that they knew I was back there and that they were OK with it. Since I don't have a CB in my MO, and because I generally want to go faster than the semis, I don't draft anymore.
(oh, and as for MPG, I didn't really notice a different in the rabbit. It already got over 40mpg, and diesel was cheap at the time, so I didn't really pay attention to it. I just cared about the speed...) ;)
See my CB install
Dan |
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| njjoe |
The other problem you have with tailing a big rig so close is a lack of forward visibility. If there is debris in the road you will never see it in time to avoid it.
-njjoe |
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| jkster107 |
Yeah, I tried it a couple times on our Christmas road trip. Good MPG improvement according to the screen, but it just felt like a really bad idea being so close.
70 [miles/hour] * 5280[feet/mile] * 1/3600[hour/second] = 102.7 feet/second
To get a mileage improvement, you have to drive at least 1 second off of the truck's bumper. eeek. If only they made transparent trucks. |
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| Stu |
| At the very least, it sounds like a good way to get a rock chip on your windshield. |
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| krush40 |
You definitely don't want to run into the back of a big rig. Check out this guys story. He got pinned between 2 big rigs.
Link |
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| jkster107 |
quote:
Check out this guys story. He got pinned between 2 big rigs.
Holy Crap.
Interestingly enough, the Mythbusters also tested something very similar to this crash. I almost wonder if the myth they tested was formed based on this story. At first glance, the firefighters didn't even see that guy's car... just a couple of trucks sitting there. Amazing story. |
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| Eric L. |
| At highway speeds, you don't want to follow too close to any vehicle, particularly one that obstructs your view of the traffic ahead. I know in big city gridlock you have people following less than one car length to prevent people from "cutting in" but remember the mythbusters test was on steady state cruising, which normally delivers good mileage anyways - its the stops and accelerating up to speed that kills mileage which is why city mileage stinks. |
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| woossh |
I can attest to drafting. I was drafting a 911 once at 140 with t-tops off and windows down (it was summer). It was very comfortable until I pulled out to pass him. When I swapped lanes the wind almost took my head off and it was like hitting a wall speed wise. I did finally get around him though.
Lesson learned. Just ride and enjoy.
Oh, got blew off by an '07 Z-06 y'day. He was drafting. |
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| vfr |
quote:
At the very least, it sounds like a good way to get a rock chip on your windshield.
And not to mention all the paint chipping you will find on the front end.
From my motorcycle experience, following a semi is like facing a sand blaster at speed. I avoid dwelling behind a semi like the plague. |
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| hotspur |
quote:
Originally posted by woossh
I can attest to drafting. I was drafting a 911 once at 140 with t-tops off and windows down (it was summer).
One can only wonder how someone can be so selfish in endangering others on public roads.. |
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| Scott-Murano |
quote:
Originally posted by njjoe
Hmmm... they also did a test where they dropped a toaster into a bathtub. Do you want to verify those results also? :2:
-njjoe
LOL that was the laugh of the day thanks:p :p |
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| Tarzan_MO |
quote:
Originally posted by ShaggyUSM
According to Mythbusters, you get DRAMATICALLY better gas mileage by driving behind (drafting) an 18 wheeler. Benefits begin at 100 ft, and steadily improve as you get closer. Drafting works! I confirmed this in the Murano using the fuel economy bar graph thingy. When NOT behind the 18 wheeler at 70 mph, the graph was somewhere between 23 and 27 mpg (depending on hills etc). Then I pulled behind a semi doing the SAME speed (70 mph) as I was before and the gauge shot up and pegged out at 30 mpg. So since it won't go above 30 on the bar graph thing, I don't know just how much I was doing because I didn't want to reset the "average mpg". This was at about 50 feet behind a semi. IT WORKS! Not just plausible, it really works!
:2: :2: :2: :2: :2: :2: :2: :2:
The test vehicle was a Dodge Magnum (v6?)
55mph control: 32mpg
100ft: 35.5mpg, 11% improvement
50ft: 38.5mpg, 20%
20ft: 40.5mpg, 27%
10ft: 44.5mpg, 39%
2ft: 41mpg, 29%
Um, yeah, but that's mostly because you're driving SLOWER, too.
Most people don't realize that the heavy-footed driving habits these days (people think they're on the AutoBahn) doesn't help the mileage.
All you gotta do it slow down and the mileage will improve automatically.
Then of course you can drift to help yourself more, but would you really get that close?
Didn't think so. Nor are many people that patient enough to take so long to get to a place these days. |
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| ShaggyUSM |
| OK, I guess people here in Mississippi drive way more aggressively than where all of yall are from. Seriously, 50 to 100 feet is NOT that close here. If you DO leave a gap bigger than that, people will just swoop in and close the gap for you. So it's actually IMPOSSIBLE (especially in the morning and afternoon) to leave MORE than 100 feet between you and the person in front. And YES it DOES work no matter WHAT speed you're driving. As a matter of fact, the FASTER you are going the more of an improvement you'll see. As speed increases, wind drag increase exponentially...EXCEPT WHEN YOU ARE DRAFTING! IT WAS JUST A COOL FACT THAT IF IT APPLIES TO YOU CAN ALSO BE HELPFUL! IT APPLIES TO ME! If I'm going to be stuck in bumper to bumper traffic (yes our bumper to bumper traffic travels 70 mph!) why not be on the bumper of a rig and save some $$$ at the same time! 100 ft is 1/3 of a football field...Good Lord! The rule is one carlink for every 10 mph...or (at 70 mph) 7x15=105 FEET!!!!!! NOT THAT BIG OF A DEAL PEOPLE!!!!!!! GEEZ! |
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| njjoe |
Yes, while it is true you can improve your highway-mpg and save fuel by riding very close to the back of a tractor trailer, there is a downside to consider.
-njjoe |
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| Corin |
| You know, at THAT point, you could turn off your engine completely and the truck can do ALL the work! Infinite gas mileage!!! :) |
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