By Molly Daly

PHILADELPHIA (CBS) – Pennsylvania drivers who fuel their vehicles with diesel are facing painful pump prices.

The owners of diesel powered cars and trucks know all too well it’s not just the green handle that distinguishes the diesel pumps from the gas, so they’re used to the higher prices.

But since mid-December, the price of a gallon of diesel has gone from an average of $3.99 to $4.34. AAA Mid-Atlantic’s Jenny Robinson says demand is one factor — and Pennsylvania’s new transportation funding tax is another:

“As of January 1st, regular gasoline taxes went up by 9.5 cents per gallon at the wholesale level, and diesel prices increased 12.9 cents per gallon.”

Despite that, gas prices haven’t changed all that much. Robinson says that’s where demand comes in.

Most non-business vehicles run on gasoline. Cold weather keeps consumers indoors, so they’re not driving as much, keeping demand and prices down. Businesses are the biggest consumers of diesel, and cold keeps them busy.

“Those are the snow plows that are clearing snow from our roads, those are the trucks that are delivering heating oil, and delivering everything else,” says Robinson.

She adds it doesn’t look as if prices will head down anytime soon, since February is when refineries traditionally go offline for maintenance.

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