UPDATE 1-U.S. gasoline demand down 1.2 pct yr/yr-MasterCard

* Gasoline demand down 1.2 pct yr/yr, up 2.1 pct wk/wk

* Average pump prices down 1 cent to $3.97/gallon

(Adds quote, detail, graphic)

By Selam Gebrekidan

NEW YORK, May 17 (Reuters) - U.S. retail gasoline demand fell last week compared with a year ago as a drop in gasoline futures has yet to translate into a significant break for consumers at the pump, according to a report from MasterCard Advisors' SpendingPulse released on Tuesday.

Average weekly gasoline demand fell 1.2 percent in the week to May 13 compared with the same period a year ago, the report showed, as retail gasoline prices dipped 1 cent on average to $3.97 a gallon across the United States. Prices were still 37.8 percent higher than a year ago.

Gasoline futures on the New York Mercantile Exchange have dropped nearly 16 percent, or more than 50 cents, this month, in part due to easing supply concerns ahead of the summer driving season.

(Graphic: link.reuters.com/dah62k )

While retail prices have not yet fallen as steeply, consumers could get some relief in the coming weeks, according to John Gamel, gasoline analyst for MasterCard Advisors SpendingPulse.

"Last year, prices fell in April but we didn't see price savings until May. We expect a similar lag this year but prices could also reverse," said Gamel.

While gasoline demand dipped against last year, it rose 2.1 percent compared with the previous weeks. Over the latest four weeks, average U.S. gasoline consumption fell 1 percent from year-ago levels, the eighth straight drop.

MasterCard Advisors, a unit of MasterCard Inc MA.N, estimates retail gasoline demand based on aggregate sales in the MasterCard payments system coupled with estimates for other payment forms including cash and checks. (Reporting by Selam Gebrekidan; Editing by Marguerita Choy and Matthew Robinson)