Martha Britt lives in Dacula, about 19 miles from her job at Gwinnett Medical Center in Duluth but just two miles from co-worker Amy Tsangarides, a nurse who shares the same shift.

As gas prices approached $4 a gallon this spring, the two met in a grocery store parking lot between their homes and began to car pool.

File (ENLARGE)

Nurses Amy Tsangarides (left) and Martha Britt of Dacula earn money from the Clean Air Campaign for sharing the ride to Gwinnett Medical Center in Duluth.

Britt, 64, and Tsangarides, 41, signed up for the Clean Air Campaign's Commuter Rewards program at Clean Air Campaign. Both earn $3 a day, up to $180 a month, for changing their commute.

Britt says she saves about $70 in gas for her Buick Rendezvous during the weeks that Tsangarides drives her Toyota Corolla to work and knows she can earn an additional $15 a week.

The savings inspired Britt to change other habits. She walks to the grocery store and pharmacy and makes fewer stops at stores with her car. She and her husband vacationed with their daughter's family to save money, too. They all piled into the Rendezvous and split the $275 gas bill to and from Florida.

Britt says shifting to a car pool commute required a few mental adjustments, but not dramatic lifestyle changes. The co-workers run quick errands together, when needed.

Even if the price of gas went down dramatically, Britt says, she wouldn't go back to her old ways.

"When I was driving my car alone, I would stop and shop and do little side trips. You just don't do those anymore," Britt said. "We're all spoiled having our own car. I think those days are gone."

— This article is a reprint from the "31 Ways to Save" series that ran in The Atlanta Journal-Constitution during July.