The premium for U.S. gasoline prices over benchmark crude has surged by more than $6 in three days, its biggest such rise in more than four years, as a series of refinery disruptions toward the end of an unusually strong summer driving season squeeze supplies. U.S. RBOB gasoline futures jumped more than 4 percent on Wednesday, even as U.S. crude futures barely gained 0.5 percent, widening the so-called crack spread between the two to $31 a barrel intraday – nearly the highest level since 2013. Before this week, the spread had slipped to below $25 a barrel, near its lowest since February, as U.S. gasoline inventories remained at relatively comfortable seasonal levels and dealers anticipated a seasonal slowdown in demand. That changed in recent days, with at least three major refineries experiencing serious upsets […]