Readers of a certain age might remember those bumper stickers with Yosemite Sam toting two six-shooters and yelling "Back Off!" He wasn't yelling "So you can burn more fuel!" but researchers are looking at how tailgating could save gas, and, in this case, are working with big rigs.

The New Energy and Industrial Technology Development Organization (NEDO) is testing what's been known in some circles as a road train program with heavy-duty trucks in Japan, The Verge says. Under the program, a convoy of four trucks are computer-programmed to drive about 13 feet apart, which cuts wind resistance and boosts fuel economy for the trailing vehicles, The Verge reports. In fact, fuel efficiency could climb as much as 15 percent through such a program. NEDO will expand such testing efforts later this year.

NEDO's efforts are similar to those that Volvo has been testing since 2009 with variants of SARTRE (Safe Road Trains for the Environment), the company's own road train concept. SARTRE involves a truck followed by three cars driving at about 13 feet apart at 55 miles per hour, and is said to cut fuel use for the trailing cars by as much as 20 percent. Volvo, which said it finalized the most recent phase of that program last September, hasn't released details on possible further testing or expansion of its road train efforts.

Check out some videos on the project below.