On the day after Christmas for the last 10 years, Richard Bartel has flown six people to the Bahamas in his private plane.

"Plane-pooling makes the vaction very economical," he says. "Round-trip transportation -- including hopping from island to island -- costs each person just $200" (compared to $356 nonexcursion fare with a commercial airline).

Bartel, who started his vaction plane-pool when he was president of the University of Maryland's flying club, continued it through the five years he worked as an air-safety inspector for the Federal Aviation Administration.

"It was such a popular thing that it gave me an idea. If one classified ad could attract that many people interested in sharing a ride, there was probably a big demand for a long-distance ride-sharing service."

Last August, Bartel, 30, hooked up with Derrick Mason, 33, a former Peace Corps worker, and Arlene Thorner, 23, a recent graduate in public relations, to start RideXchange, a nonprofit group that matches prospective travelers with drivers, pilots and passengers going their way.

With $15,000 in seed money from the Virginia Department of Energy, they were able to move in January from Bartel's home in Northwest Washington to an office in Silver Spring. Since then they've matched about 200 people for trips, with the most popular destinations Florida, New York and Chicago.

To use the service, prospective travelers pay a one-time registration fee of $5($10 after March 31) and a deposit of $10. Each time a member lists a trip with the RideXchange computer, $1 is subtracted from his or her account. Referrels cost $2 per search, for anywhere from one to 20 names.

"There is no charge for making changes in a listing, or if there are no referrals at the time of the search," says Thorner. "When the $10 is used up, the member must deposit another $10. Making travel arrangements is up to the members."

Thorner is one of four drivers marking American Energy Week this week by driving from Los Angeles to Washington, D.C., in cars donated by Ford, powered by synthetic fuel. Racecar drivers Janet Guthrie and Lynn St. James and Indianpolis mechanic Kay Bignotti also are scheduled to drive in the eight-day "cross-country rally for ride-sharing," and transport passengers from city to city on the way.

Two cars will be powered by gasohol, one by methanol and one by ethanol. The ethanol is donated by MarCam Industries Inc. of Philadelphia, an alcohol fuel marketing firm, to demonstrate synthetic fuel's effectiveness for long-distance travel.

One factor they plan to stress, says Thorner, "is that the RideXchange takes every possible precaution for the security of its members. We require identification -- driver's license and Social Security numbers and another valid ID -- from each member. The fact that someone has to pay to use the service helps ensure that those who join are interested in travel.

"We also encourage people to get to know each other by phone or in person, especially if they are going on a long trip together. That way they can iron out other things, too, like the kind of music they like or if they're smokers or nonsmokers.

"We only give out first names and phone numbers," adds Mason, who used ride-sharing through college to get from his home in Massachusetts to school in Oregon. "Students around the country have been doing this for years through listings on ride-boards and radio stations.

"We're expanding on that idea. So far we've attracted a wide range of people -- young couples, retirees. Many people want companionship, in addition to sharing costs. Having four eyes on the road can be safer."

RideXchange recommends that members check with their insurance companies and possibly increase liability limits to cover extra passengers.

"As long as the carpool fees aren't more than the fair share of gas, oil and car depreciation," says a spokesman for the Insurance Information Institute, "ride-sharing should pose no insurance problem."

The group is seeking a federal grant to open a downtown ride-sharing center this summer, in cooperation with the Metropolitan Washington Council of Governments.

"It would house the commuter ridesharing program, our long-distance ride-sharing and sell Metro passes," says Bartel. "We're hoping also to develop ride-sharing referrals through the cable TV system."

Another group that launched a similar service -- the Portland, Ore.-based Travel Mate/The National Carpool Association -- went bankrupt last year amid charges of misrepresentation and misuse of customers' credit cards.

"As I understand it, they over-extended themselves," says Bartel."And they mishandled the operation."

The RideXchange's success, he notes, will depend on building a network of satisfied members. Bartel, who quit his GS-12 job in November for a $7,000-a-year salary with RideXchange, has faith that enough people will get involved.

"It's a philosphical thing with me. Since resources in general are becoming scarce, I think Americans' whole mentality about sharing has to change.

"We've been so individually oriented, each with our own house and our own car. But if we want to maintain our standard of living and travel, sharing will become a civic duty."