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Just saw a someone make a post declaring drafting is stealing from the vehicle you are following. Did not back it up with a link and I'm suspicious if the poster really knows for sure.

It's worth checking into. A definitive answer may be found Googling. I'd think the Air Force would know for if lead pilots use more fuel in formation than solo - the practice pre-dates World War II.

If that does not work, maybe one of us can visit Wayne sometime and draft his Ranger. :D

I won't discount the "stealing" remark out of hand, but I figure a wake is a wake.

If you saw that non-linked post on Priuschat, it appears from subsequent posts that the opposite is true. Drafting apparently provides a (small) benefit to the lead vehicle, according to a number of posters.

A biker chimed in and mentioned that it is true for bikes as well. Getting out in front to let others draft off of you may be tiring, but LESS TIRING than riding alone.

Chuck.........until it's resolved, I've filed a request to have all of your MPG tanks due to drafting in the Metroplex placed with a Roger Maris-like asterisk (*). :) Just kidding.

Not a very good comparison, but at the two (potentially) fastest NASCAR tracks (Daytona and Talledega), where they use carburetor restrictor plates to limit horsepower and speed, aerodynamics are such that drafting actually helps the lead vehicle. A car rarely can pass another at full speed without another car aerodynamically "pushing" it from behind, and cars cannot pull away from the pack individually.

Chuck.........until it's resolved, I've filed a request to have all of your MPG tanks due to drafting in the Metroplex placed with a Roger Maris-like asterisk (*). :) Just kidding.

:D

Actually, my drafting is done outside of D/FW on long trips - traffic moves too much or is too fast to make drafting worth it on commutes.

The quick explanation, like I gave on PriusChat, is that drafting modifies the low pressure region at the rear of the lead vehicle. Rather than circulating fully, the air stream continues over the drafting vehicle and reduces the severity of the low pressure region. That means lower drag forces on the lead.

Hi Chuck:

http://www.cleanmpg.com/photos/data/501/2007_Daytona_500_Winner.jpg

___As Jim and Tim eluded too, this year’s Daytona 500 was won by Kevin Harvick over Mark Martin at the finish due to a huge bump draft from Matt Kenseth on the last lap.

___If you can smooth out the airflow being a draftee, both vehicles benefit although I have read of non-science oriented semi-drivers saying the opposite.

___Good Luck

___Wayne

...If you can smooth out the airflow being a draftee, both vehicles benefit although I have read of non-science oriented semi-drivers saying the opposite....

Maybe some of those truckers say "I suck" (their airflow). :D

I have done a whole bunch of century bike rides and races, many sub 4 hour, and several on a tandem. Drafting is an accepted and expected practice on these rides. I can't say that I ever felt any "HELP" from the rider behind me, but I sure felt the help from the rider ahead of me. On the other hand I have felt some "HELP" from 18 wheelers and large SUVs that "TAILGATE" me. (we "draft" they "tailgate") :) I think the difference is the big blunt front end of the truck and SUV creates a large enough high pressure area in front of them to fill in the low pressure area behind the car in front of them. The bike is not large enough or fast enough to create a large enough high pressure area to fill in the gap between the two bikes even if they are only 1 to 4 inches apart.....Louis

Hi Louis:

___I am not sure if you have seen some of the pics Chuck has taken or not but here are some great ones …

http://www.cleanmpg.com/photos/data/525/drafting.jpg
I think you may know the crazy SOB behind the wheel of that Insight ahead :D

http://www.cleanmpg.com/photos/data/2/Truck_Drafting_Insight.jpg
Who says Insight’s aren’t great draft targets?

http://www.cleanmpg.com/photos/data/2/Resize_of_House_Drafting.jpg
Saw a house going down the road and took advantage of it in the only manner I know how! House Drafting ;)

___The last one was on our way back from Sebring, Florida (Gary G., Bill Kinney and myself for a get together at the 12-hours of Sebring) just over a year ago.

___Good Luck

___Wayne

Take the last picture and imagine instead two 18-wheelers directly infront of you and a 3rd beside you in light to moderate rain. They deflected it - my car way dry.

If you saw that non-linked post on Priuschat, it appears from subsequent posts that the opposite is true. Drafting apparently provides a (small) benefit to the lead vehicle, according to a number of posters...
.

I remembered this when looking at

http://gcep.stanford.edu/pdfs/ChEHeXOTnf3dHH5qjYRXMA/10_Browand_10_11_trans.pdf

Graphs on pages 9-14 suggest slight savings for the lead vehicle under several circumstances.

Safety nag: at night it can be difficult to see debris launched by tires of preceeding vehicle. Had one such experience with several chunks of tire treads, all of which miraculously missed the little Prius. Maybe nighttime drafting is not such a good idea...

OT: In addition to the above document, there are several (expensive) studies showing worthwhile fuel savings from truck aero mods. Sadly, few have yet been implemented.

DAS

We can't forget, close in drafting isn't the only kind of drafting. There are other drafts that while they don't provide a huge gain, do provide a little benefit and are very safe. I urge anyone not familiar with these other drafts to go here: http://www.cleanmpg.com/forums/glossary.php?s=&do=searchresults&search=Draft&searchoptions=3

We can't forget, close in drafting isn't the only kind of drafting. There are other drafts that while they don't provide a huge gain, do provide a little benefit and are very safe. I urge anyone not familiar with these other drafts to go here: http://www.cleanmpg.com/forums/glossary.php?s=&do=searchresults&search=Draft&searchoptions=3

Thank you for mentioning this, Tom. Indeed there are ways other than closely following a big rig.

I've had reports on PriusChat that lanes with more vehicles get them better fuel economy than empty lanes (at a steady speed - of course)

Thought of you all yesterday evening. On my way home a shortie double trailer passed me and then swung back into "my" lane before the second trailer was fully past me. Had to brake to avoid being hit. Couldn't tell if he was mad at me or simply not used to the length of a double rig.

I don't normally draft (for safety and to avoid stonepecking my beloved Insight), but this was too perfect an opportunity to miss. Figured a double would give a bit more draft, would be easier to keep up with on the hills, and might not brake as quickly as a single rig.

So I drafted him - tight but not really close - for the next 20 miles at a steady 60-65mph, and got a nice 70mpg despite the cool weather here in CT. Blinked a "thank you" - which I'm not sure was appreciated - as I exited.

But I'm not going to make a habit of it.

How is the relationship between 55MPH steady state single car and 65MPH draft? Most of the trucks in my area run about 5MPH over the posted speed or are limited to 65MPH in a 70MPH zone.

Should I stay at 55MPH, or increase speed to catch a savings in reduced Cd?

Hi Fredness:

___All drafts are relative to the type of vehicle you drive as well as the target, its speeds, the road conditions, the wind direction and speed, weather conditions and most importantly traffic. On a warm day with clear traffic, a HS P&G is a gimme for 60 in the Accord for my drive home. At 50 mph and naked, she will easily hold 50 mpg while DWL and DWB. At 60 mph, about 40 mpg. It is that drastic with the Accord. A draft target will show a higher FE on the iFCD but the target is never exacting enough to make it work out for the 60 mpg segment all the way home. In mid-winter with heavy headwinds and cold temps including snow/sleet/rain, a target is about the only thing that will save a segment below 65 mph. Anything faster and I can crawl through the mire at 48 - 52 and do better. Traffic sides and Surfs really help in that situation.

___You will have to experiment w/ an SG-II attached but like all advice wrt drafting, you really do have to be extremely careful as one slip and it is going to cost you a lot more then the lower fuel consumption and emissions reduction you wanted to achieve. Stick with the Distant, Surf, and Traffic sides while HS P&G’ing when and where appropriate and the numbers will prove themselves to be better over time for most.

___I want to add here that a D-FAS is not nearly as dangerous as it has been made out to be these past few months as you are usually only pulling into a Distant draft and then falling back. Not to say it is less dangerous then just driving with huge buffers (DWB) but it can make a 58 mpg segment into a 60 mpg segment with a few well placed and calculated applications.

___Good Luck

___Wayne

My style doesn't involve IG-I, or "Gliding". All IG-II, ICE-On, All in gear.
I approach until I can feel the Focus buffeting from the downforce and continuing until it stops (fall in the low pressure zone). Varies with speed/target. 2.0 to 1.0 seconds, so it's between your Close-in and Distant.