Hyundai said Tuesday that customers in the U.S. who buy or lease its vehicles by Aug. 31 will receive a gas card that lets them buy fuel at $1.49 a gallon for a year, a promotion to win over consumers worried about volatile prices at the pump.

Customers who enroll in the promotion, which launches today, will receive a gas card that bills gas purchases at $1.49 per gallon of regular-grade gas, regardless of the pump price. Though all eligible vehicles take regular gas, customers can buy mid-grade gas at $1.64 a gallon and premium gas at $1.79 a gallon, Hyundai said.

The new incentive is the second attempt this year by the Korean automaker to take pressure off apprehensive and cash-strapped buyers. In January, it launched its "Assurance" program, which offers to take back vehicles under certain conditions from Hyundai customers who lose their jobs.

The gas guarantee would save consumers $1.14 a gallon, or 57 percent, off Tuesday's average price of $2.63 per gallon of unleaded, according to the auto club AAA, Wright Express and Oil Price Information Service. However, the savings could rise or fall depending on the future direction of pump prices.

Though Hyundai's sales have fallen in recent months, it has scooped up market share. Hyundai sales are down 8 percent for the first five months of the year, well below the industrywide decline of 37 percent. Its market share has surged to 4.2 percent from 2.9 percent.

Hyundai said its gas lock incentive program will apply to all of its vehicles except its Genesis luxury sedan and coupe.