Does drafting behind an 18 wheeler help increase highway gas mileage?

Here are some answers:
Yes at distances less than 100 feet, but it is not safe because at 100 feet your response time is only 1.25 seconds.

Discovery's Mythbusters found an 11 percent savings by following a truck at 100 feet.

A hundred feet seems awfully close, but I didn't find any tests done at 150 or 200 feet, so I suppose at any distance over 100 feet, there is no benefit.

Increasing gas mileage isn't much of a concern right now, anyway. I was driving on the highway yesterday (Memorial day) for a short trip and at 65-70 mph, I was being passed like my car was sitting still.

I just don't think $4 gas is all that big of a deal. If it were, you'd see people changing their habits. I think the news media is blowing it all out of proportion since they like to turn the most insignificant events into doomsday (see: weather related stories like "Thunderstorm 2006" or "The Rain Shower of 2008").

You don't hear Europeans whining about gas prices, and they have been paying $7-8/gallon for at least 15-20 years. I'd like to see gas here go up to $7-8 gallon and see what the general response is. My prediction is: maybe 5-10% will change their habits, but everyone else will keep driving SUVs, driving at high speeds, and driving frequently. Here are some reasons why nothing will change:

a) The U.S. infrastructure was built on cheap gas. Most people can't change where they live or work quickly, so they'll continue to deal with urban sprawl.
b) Most people think in the short term financially. Thus, if you had to take a big hit to sell your SUV to get a smaller car, you'd rather pay the incremental gas cost than lose a few thousand at once.
c) My spending habits may not be typical, but currently gasoline is 3.5% of my monthly spending (includes non-discretionary), with an estimated 10-12,000 miles driven per year. Whoop-te-doo.

The only people hurt by gas prices in my opinion, are people who are earning minimum wage. The rest of us, who may have to sacrifice buying that fifth flat screen tv this year, are not suffering, regardless of what the news media says.