Drafting: stream of cars vs semi

[Geonerd]

Originally Posted by theholycow

Is that the extremist who is often shown on the news with his stock Honda Accord getting something like 75mpg?

Yea, that's the guy. Wayne Gerdes.
He has a pretty good site, similar to Gas Savers: http://www.cleanmpg.com/

-Moo

[palemelanesian]

I too have noticed a negative push right when the tractor passes my car. It's somewhere between the nose and the tractor-trailer gap. I like to swing a little wide right as he begins passing, and then return to my position once the trailer is beside me.

Wayne Gerdes - you have to filter those news reports though media sensationalism. I've driven with him, and it's nothing crazy at all. He is driven and focused, but not crazy.

[GasSavers_RoadWarrior]

I think it's a kind of "bow wave" of denser air. Seems to me to come back at an angle from the front of the tractor, so depends on how far over in the lane you are. If he's keeping to the middle of his lane, you can go on the right hand lines of yours and it's a lot weaker and further back, whereas if you're hanging left and he's hanging right it can toss you all over the place...

I noticed however, that after I put turbulation strips on the back end of Marvin, this effect was MUCH reduced. I didn't see any MPG gain on that due to the tranny screwing up and finally crapping out. But it felt like I was a lot less affected by crosswinds, and last tank was on the high side despite mechanical issues.

[neverendz]

I remember watching Mythbusters. They did a thing on drafting for better MPG.

Big Rig Myths (June 6, 2007)
In Exploding Tire of Death, Adam and Jamie try to find out if an exploding truck tire can kill. Meanwhile, Kari, Tory and Grant investigate another fuel efficiency fable.

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.


Interesting episode. I don't remember what the benefits were at a safe distance. I'll watch it again tonight.

, Bill

[theholycow]

Testing by members here and elsewhere has shown that being too close is worse than not drafting at all. Reports of best draft are between 1 and 3 seconds following distance.

[slurp812]

Iv felt, and measured this effect (with SGII) a few times. I was driving with 10 to 15 cars all doing 70 mph I was getting mileage similar to myself at 60 or so. I thought something was reading wrong!

[1cheap1]

Originally Posted by Geonerd

Several have mentioned having a in front and a truck behind them, as well. Do you have a death wish?? Saving a few oz of gas is nice, but is it worth getting squashed like a bug? Truckers enjoy great visibility (assuming the driver is alert enough to use it!), but a semi simply cannot stop as quickly as your car. If a pileup of any sort occurs, you're toast.

In a more general sense, many hypermiling techniques will produce accelerated wear and tear on your car. Anytime you stop the engine, you're cycling the ignition switch, starter or clutch, and collapsing the oil film that keeps your engine alive. Even a warm start will generate far more wear than simply leaving it to idle.

Evey time I see a video of King Hypermiler Wayne, I think, "That guy has obsessive-compulsive issues!" (He jams the car in into drive immediately after a cold start; he putts down the road trailing a dozen pissed off commuters, etc.) Yet time and time again, I see people wanting to do it just like he does, to achieve the same level of FE. Think people, THINK! As with anything in life, blind pursuit of an objective seldom works out in the long run. Go save gas, but try not to destroy your car, yourself, or the sanity of your fellow motorists in the process!

Here in Socal the 710(Long Beach) is the mecca of container trucks. Usually thousands are going each way and you almost cannot avoid them. To exit from the fast lane is a challenge because they tail gate each other at a very small distance. The best way is to get between them early so you really have no choice but to draft. They even occupy the next to the fast lane if it gets to slow. Just have to make the best of a crowded situation.