—Glenda Bell, Atlanta
A: Higher worldwide demand, especially in China, India and Europe, is part of the reason the cost of diesel fuel has increased from an average of $2.99 a gallon in 2010 to around $4.15 a gallon this year, according to the U.S. Energy Information Administration (EIA). Other reasons for the higher cost of diesel: The U.S. has decreased the amount of sulfur in diesel fuel, which resulted in higher production and distribution costs; and the federal tax is 24.4 cents per gallon, 6 cents higher than the gas tax, according to eia.gov. Diesel fuel is considered "middle of the barrel," as are all distillates, Maureen Klein, a spokeswoman with EIA told Q&A on the News in an email. Other products, like residual fuel and asphalt, are considered to come from the bottom of the barrel, she said. Diesel fuel is closely related to heating oil, but is more costly to produce because of the extra processing to remove sulfur. "One barrel of crude oil, when refined, produces about 19 gallons of finished motor gasoline and 10 gallons of diesel," among other products, according to eia.gov.