The average Atlanta household using mass transit saves $9,129 a year by not driving, according to a transit advocacy group.

That’s $3,000 more than the average American household spends on food, said a report by the group, the American Public Transportation Association.

The savings come even with the recent slight decline in gas prices. “With the price of gas hovering at 89 cents higher than last year, transit users have an increased savings of $411 annually compared to this time last year,” according to a statement released by the association.

The study looked at the cost of monthly transit passes versus what AAA calculates as the average cost of driving and parking. That includes gas, maintenance, tires, insurance, license registration, depreciation and finance charges.

Part of the savings arise because the study assumed that a household that went from driving to transit would give up one car, no longer spending money to register and insure it, said a spokesman for APTA, Mantill Williams.

The data is far from an exact picture, and the study used at least one shortcut. But at least for Atlanta, without that shortcut the report might show even greater savings from mass transit.

Atlanta’s savings from transit ranked 17th out of 20 cities in spite of Atlanta’s long commutes.

Williams said the report takes into account the specific parking and gas costs for each city, which in Atlanta are relatively low. But, he said, it uses a national average for the commute length. Georgia’s average commute is the sixth-longest in the nation, worse than California’s, according to the most recent census figures.

“The ones that rate higher are usually because of a higher cost for gas and a higher cost for parking,” Williams said.

Boston ranked first in the transit savings study, with a household savings of $13,490 a year.

In another study released this summer, the National Resources Defense Council said Georgia ranked third in the nation for the highest portion of household income spent on gas.

Some Georgians are taking advantage of transit savings in the face of higher gas prices. Transit agencies across metro Atlanta are seeing increases in ridership. And for the first time in decades, the Federal Highway Administration this year is reporting an extended decline in the number of miles Americans are driving.