The Associated Press, via Yahoo News, has a story with list of ideas to improve gas mileage.

http://news.yahoo.com/s/ap/20070529/ap_on_re_us/hypermilers_glance_1

#8 on the list is “Draft sensibly behind tractor-trailers”.

I ask this out of honest curiosity; is there really a sensible way to draft behind a tractor-trailer? I understand the gas saving benefit of doing this. I ride a bike and am fully aware of how much less energy is expended peddling in the draft of another bike. It’s significant.

But is the risk of collision worth advocating this activity, even with the caveat that it be done “sensibly”?

And what exactly does “sensible” mean in this case. How do you sensibly tailgate a tractor-trailer? In what circumstances is this safe activity? How can the average driver know what is sensible versus what is unsafe. Is there some recommended distance from tractor-trailers which is both safe and provides benefit for gas mileage?

Can anyone clarify this for me?

Here, by the way, is a good site:  

http://www.hypermiling.com

As far as I can see, there's no reference here to drafting tractor trailers.