Diesel dropped 2.3 cents to $3.778 a gallon, the lowest national average price in more than two years, the Department of Energy reported Sept. 22.
Diesel, which has risen just twice since April, has plunged 24.3 cents since mid-March and is 17.1 cents below a year ago.
The retail average price is the lowest since trucking’s main fuel averaged $3.695 on July 16, 2012.
The price declined in all regions, led by a 3-cent drop in the Midwest to $3.713, DOE figures showed.
It fell 2.9 cents on the West Coast to $3.99, marking the first time it’s been below $4 in that region since June.
The decline came as oil prices fell to their lowest level in more than a year.
Gasoline, meanwhile, dropped more than a nickel, sliding 5.5 cents to $3.353 a gallon, the lowest level since February, DOE said following its weekly survey of filling stations.
Gas has plunged 35 cents since June and the downturn — the biggest single-week decline in 10 months — left the motor fuel 14.2 cents below the same week last year.
Crude futures fell 89 cents Sept. 22 to $91.52 a barrel on the New York Mercantile Exchange, the lowest closing price since May 1, 2013, Bloomberg News reported.
Each week, DOE surveys about 400 diesel filling stations and 800 gasoline stations to compile national average prices.