Fuel prices show few signs of stopping their recent decline, and if expectations about oil prices into next year come to fruition, the ride may continue for a lot longer.

New U.S. Energy Department numbers issued Monday show the average cost of on-highway diesel is down for seventh consecutive week, falling 2.1 cents from a week ago, to $3.635 per gallon. This is its lowest price since February 2011 and is in sharp contrast to the high so far for 2014, hit in March, of $4.021 per gallon.

Including weeks when the price of diesel was unchanged from the week before, it has been 18 weeks since the last increase. The latest average price is 23.5 cents less than the same time a year ago.

The only region of the country where diesel prices increased last week is the Midwest, up 0.5 cents for an average of $3.611. The largest decline was 4.4 cents in the Central Atlantic states, falling to an average of $3.693.

Prices range from a low of $3.563 in the Gulf Coast region, down 2.6 cents from last week, to a high of $3.799 in the West Coast region, down 3.6 cents.

The average price or regular grade gasoline is also plummeting, falling 6.4 cents this week from the week before. It's 23.8 cents less than a year ago at $3.056 per gallon. The high for gasoline so far this year was in April when it hit $3.713.

Regionally, gasoline prices are down in all parts over the past week and range from a low of $2.83 in the Gulf Coast states to a high of $3.324 in the West Coast region.

As for the price for the mother of motor fuels, crude oil, it barely moved on Monday, shedding just 1 cent at the close of trading in New York and settling at $81 per barrel. However, compared to last Tuesday’s opening price, it is down $1.76, with expectations it will continue moving lower. Much of the reason is there is increasing evidence of rising supplies of crude, while worldwide demand growth is expected to be slower.

The investment firm Goldman Sachs on Monday said it believes the price of the U.S. benchmark crude will drop as low as $70 per barrel by the spring. If this happens this would be the lowest price for U.S. crude since 2010. Just four months ago it was past the $100 per barrel level.