* Gallon of gas up 20.32 cents in two weeks to $3.7950
* Future price increases may be more limited, or cease
By Jonathan Stempel
Feb 24 (Reuters) - Americans are paying 20 cents more per gallon to fill up the gas tank than they did just two weeks ago, but the two-month upward trend in pump prices may be about to end, a widely followed industry analyst said on Sunday.
The Lundberg Survey said the national average price of self-serve, regular gasoline was $3.7950 per gallon on Feb. 22, up 20.32 cents from two weeks earlier, and above the $3.6917 price at this time last year. Diesel fuel cost an average $4.17 per gallon, up more than 10 cents from two weeks earlier.
Gasoline prices have now risen 53.71 cents, or 16.5 percent, in the last nine weeks, with most of that gain coming since late January. The survey of about 2,500 gas stations comes out every other or every third week.
Trilby Lundberg, who conducts the survey, said prices have risen mainly because refiners have idled capacity to perform maintenance ahead of the spring and summer driving seasons.
But she said the latest increase masks a drop in wholesale prices over the last few days.
"I think I can see a light at the end of the tunnel," she said in a phone interview. "Refiners are passing through some of these cuts to their marketing and retail customers. In my expectation, retailers will be able to pass through wholesale price cuts in the near future. There is reason to suppose that price increases will be smaller, or maybe even cease."
Brent crude prices closed Friday at $114.10 a barrel, down 3 percent for the week, while U.S. crude futures settled at $93.13 a barrel, down 2.8 percent.
The direction of prices will depend in part on the ability of retailers to rebuild margins, the difference between what it charges and pays for gas, taking taxes into account.
Lundberg said the typical margin on regular grade gas this year fell as low as 8 cents a gallon, an unsustainable level, as retailers resisted passing on all their costs to motorists.
But she said the typical margin has rebounded to slightly more than 13 cents a gallon, close to the 14 cents to 15 cents more common in 2011 and 2012.
Gasoline prices per gallon peaked in 2012 at $3.9671 on April 6, and the all-time high remains $4.112 on July 11, 2008. Lundberg said neither level appears to be in jeopardy in the near future.
The lowest average price for a gallon of unleaded gas in the 48 contiguous U.S. states was $3.23 in Billings, Montana, and drivers in Los Angeles, paid the most to fill the tank at $4.29 a gallon, Lundberg said.
The survey is done in Camarillo, California. (Reporting by Jonathan Stempel in New York; Editing by Maureen Bavdek)