New York drivers filling up with premium gasoline are paying 85 cents more than the regular stuff, a penny shy of the record, according to American Automobile Association data.

The high price for premium is likely a result of maintenance work at regional refineries including those owned by Irving Oil Ltd. in the Canadian Maritimes and Delta Air Lines Inc. near Philadelphia, said Chris Barber, head of refining and renewables at consultancy ESAI.

Refiners also have been focused on chasing strong diesel margins at the expense of making the high-octane blending components that go into premium gasoline, Barber said.

The premium is widening at a time when regular gasoline has taken a hit from demand destruction. “With regular prices dropping, premium prices stay ‘sticky’, leading to a higher price spread,” said John Auers, managing director of refined fuels analytics at consultancy RBN Energy.

The New York premium dwarfs those elsewhere: in California, premium gasoline commands not quite 40 cents more than regular.

Less than 10% of cars on US roads require premium gasoline, usually luxury for high-performance models, according to Greg Brannon, director of automotive engineering at AAA. However, some drivers use it out of a mistaken belief that it’s better for their cars.