The national average of a gallon of regular gasoline rose to $3.9671 on April 6, according to the survey of about 2,500 gasoline retailers.

That was smaller than the 11.49-cent increase in the prior survey for the two weeks ended March 23.

"If crude oil will stay where it is then gasoline prices will peak very, very quickly, if they have not done so already," survey editor Trilby Lundberg told Reuters on Sunday.