The downside of drafting

[FoutsNC]

I know there are a least a few on here who draft the big rigs to save a couple of MPG from time to time.  This video might make you think twice about the trade offs involved in this method of saving a few cents.  For me, it's just not worth the risk

 

 

[ptjones]

The problem is not drafting, It's not paying attention to the road in front of you. You shouldn't drive any closer than your reaction time and you deffinately can stop faster than a Semi. Crash test don't count for reality, there just a deminstration what could happen if you aren't paying attention. BTW it is closer to 3-4mpg at 70mph+

Edited March 16, 2013 by ptjones

[dtorres]

Drafting is very dangerous and absolutely not worth the risk. Myth Busters did a test and found that the decrease in drag was very very small. They found that to get a noticeable difference in mpg you had to be going freeway speeds and be less than 5 feet from the rear of the truck bumper. Even they had a hard time maintaining that distance at speed in a controlled environment.

Edited March 16, 2013 by dtorres

[plus 3 golfer]

.... Myth Busters did a test and found that the decrease in drag was very very small. They found that to get a noticeable difference in mpg you had to be going freeway speeds and be less than 5 feet from the rear of the truck bumper. ...

 

Your facts are incorrect.

 

Drafting behind a big rig will improve your car’s fuel efficiency.

CONFIRMED

To test this myth, the build team procured a car, a big rig, and a device that could measure a car’s fuel efficiency. They then drove the car behind a moving big rig at various distances ranging from 100 to 2 feet and measured the amount of fuel the car consumed. The Build Team discovered that the closer the car was to the big rig, the less drag is produced, thus the more fuel saved. At just ten feet, the car managed to increase its fuel efficiency by 40%. Drafting at two feet was slightly lower than the ten foot distance, mainly because Grant had to keep working the car pedal to maintain distance from the truck. However, that did not dispute the fact that drafting actually can increase your car’s fuel efficiency. However, the Build Team has warned that drafting is incredibly dangerous because the truck driver may not able to see you and you may not be able to react in time if the truck were to make a sudden stop.

 

[plus 3 golfer]

.... Myth Busters did a test and found that the decrease in drag was very very small. They found that to get a noticeable difference in mpg you had to be going freeway speeds and be less than 5 feet from the rear of the truck bumper. ...

 

Your facts are incorrect.

 

Drafting behind a big rig will improve your car’s fuel efficiency.

CONFIRMED

To test this myth, the build team procured a car, a big rig, and a device that could measure a car’s fuel efficiency. They then drove the car behind a moving big rig at various distances ranging from 100 to 2 feet and measured the amount of fuel the car consumed. The Build Team discovered that the closer the car was to the big rig, the less drag is produced, thus the more fuel saved. At just ten feet, the car managed to increase its fuel efficiency by 40%. Drafting at two feet was slightly lower than the ten foot distance, mainly because Grant had to keep working the car pedal to maintain distance from the truck. However, that did not dispute the fact that drafting actually can increase your car’s fuel efficiency. However, the Build Team has warned that drafting is incredibly dangerous because the truck driver may not able to see you and you may not be able to react in time if the truck were to make a sudden stop.

 

[C-MaxJaxon]

You will only save about $1 of gas per 100 miles of driving with the 11% increase. That is not worth the risk in my opinion.

 

The numbers are going to vary depending on the trailer, the car following, their driving speed, and the speed and direction of the wind, so we don't know what the real world results are going to be.

[shaners]

The other downside to drafting is stone chips in your paint and broken windshields!

[wab]

When we had our MKX I would play with the tailgaters/drafters/sleepers/texters.

 

Coming out of small west Texas towns I noticed that often we would have a car attached to our bumper (makes me very nervous :nonono: @ 60+ mph).

I started setting the cruise at 65 (they luv it) then slowly bump the mph up 1 mph every couple of miles.

 

Got several up to 80 :runaway:  before they realized anything was happening.

I always slow down to 65 hoping they will reattach.

Got 1 up to 75 TWICE :doh:.

[dtorres]

I stand corrected it was 10 feet not 5 feet. If you feel safe driving 10 feet (about one car length) behind an 18 wheeler go for it. I'll spend the few extra dollars on gas and eliminate the risk.

[C-MaxJaxon]

If the truck driver can't see you in the side door mirrors, you are in a dangerous place and probably making the driver nervous. If you are so close that you can't see the truck's side mirrors, you are too close.

[Max Power]

20 or 50 feet seem safe and there is still some gain.  I would never work to maintain a draft.  Invariably the semi will hit slower moving traffic and the effort for both of you to pass may negate your gains.

 

If I drove 6 lane highways all the time I would try to make a go of it in the center lane.

[HannahWCU]

I try to give myself a one second space between me and the truck in front of me. I see about 5% increase in FE. Of course this is dependent on traffic, weather, etc.

[wab]

I try to give myself a one second space between me and the truck in front of me. I see about 5% increase in FE. Of course this is dependent on traffic, weather, etc.

 

Bet you make use of the ABS feature A LOT. ;)

[plus 3 golfer]

I stand corrected it was 10 feet not 5 feet. If you feel safe driving 10 feet (about one car length) behind an 18 wheeler go for it. I'll spend the few extra dollars on gas and eliminate the risk.

Agree, I would never drive 10 feet or even 20 feet behind at freeway speeds. At 88 feet per sec. at 60 mph, for an average reaction time of 1/4 second, that's 22 feet before one starts to remove foot from accelerator after seeing the issue..  Then probably a few tens of a second to actually step on the brake pedal and start slowing down.  Yes, a truck can't stop instantaneously and continues moving forward, but that is cutting it close.

 

I've drafted in my TDI (Cd=0.31) at various speeds (65 - 75 mph) at about 50+ feet and I can see about a 20% jump in instantaneous mpg.   The issues I have are 1) it takes concentration / alertness to maintain a 50 foot distance so others don't cut in between if the interval increase too much and 2) since trucks typically run at the speed limit and go slower up hill, travel time increases.   I typically run 3-5 mph above the speed limit on my cross country trips of 2080 miles one way with one night layover.  So, I may draft for a few miles but as soon as the truck loses speed, I'm gone as if I continue running that slow for hours on end I will likely have to spend an additional night on the road and the fuel savings by drafting and lowering my speed is offset by an extra night lodging. 

Edited March 16, 2013 by Plus 3 Golfer

[JAZ]

As I once sadly discovered, if the vehicle I'm tailgating strikes the vehicle ahead of it, I cannot stop in time by braking, regardless of my reaction time.

[HannahWCU]

<blockquote class='ipsBlockquote'data-author="wab" data-cid="12464" data-time="1363456009"><p>

Bet you make use of the ABS feature A LOT. ;)</p></blockquote>

 

Actually, never had too. Don't intend too either. As another poster says, you must keep a close eye on traffic and pay close attention to driving. If I can't do either, I don't follow trucks. I don't follow trucks everytime I get on the highway, but if an opportunity presents itself, I try to take advantage of it. Again, as long as the conditions are right (daylight, goods weather,lack of traffic, etc.). I see people all the time tailgating. They are MUCH closer than I am. Not saying its right, but how many people leave at least 2 seconds space to the car in front of them ALL the time?

[StoBro2]

I remember from years ago a good rule of thumb was to allow two seconds of space between yourself and the car you are following on the highway. It's much easier to gauge than a certain number of car lengths at a certain speed. At 60mph (88fps) that translates to 176 feet, or about the length of three eighteen wheelers. According to the Mythbusters data:

 

To get an MPG gain of approximately 20% (say, from 36mpg to 43mpg) you would have to cut that interval to 50 feet, or a little more than half a second at 60mph.

To get an MPG gain of approximately 27% (say, from 36mpg to 46mpg) you would have to cut that interval to 20 feet, or a little less than a quarter of a second at 60mph.

 

I"ll stick with my 1.5 to 2 second interval.

[rfruth]

One of the risks is the big rigs can clear stuff on the roadway 4 wheelers may not be able to (tire caucuses etc.) - if you want to draft see if its okay with the trucker first (at a rest stop or use a CB radio) some don't want someone on their tail, if okay see if the'll change lanes or flash their lights to alert you of something unusual is about to happen.  

[PWBarrett]

Way back when my brother was a teenager he told me that drafting on a motorcycle could actually pull the bike along if you got close enough.

You'd really have to be insane to do that though.

[Wingrider01]

The other downside to drafting is stone chips in your paint and broken windshields!

 

More importantly here it is a 250.00 ticket + points for careless and reckless driving, tripled if in a posted work zone.

[valkraider]

I was not even drafting and one time a semi drove over a road gator (rubber from a blowout) and it flew up into the air. I was a ways back and had enough time to hit my brakes. I was in a VW New beetle and it took out my lower grille and fog lights. If I had been drafting it probably would have gone through the windhshield, and if I had been drafting on my motorcycle I would have been dead.

 

When behind a semi you can't see the road ahead. Even if you never hit the semi, you could hit misc. road debris.

 

I have come across chairs, window air conditioners, bicycles, car parts, and all other kinds of debris that I steered around safely - because I could see them...