If there is a clear sign of the economic slowdown, it is the drastic drop in energy costs for motorists and those who heat their homes with oil as demand continues to wane.

In one of the few bright spots in these tough times, gasoline prices have plunged more than half from a record high of $4.08 on July 7, which has encouraged motorists to hit the road more and reduced the demand for more gas-friendly vehicles.

AAA Southern New England's weekly survey Monday found the cost of a gallon of regular, self-serve gas in Massachusetts dipped for the 15th consecutive week, bringing it to a five-year low. The average cost is now $1.62, and some area gas stations are selling for less than $1.60.

Before the sharp decline that began Sept. 29 and saw double digit decreases many weeks - including an eye-popping 31-cent drop - the cost was $3.55. However, in what could be a harbinger, the weekly price drops have run in the single digits the last few weeks.

A year ago, the average per gallon ran $3.03, a time when just about everyone expected the days of gasoline below $2 a gallon were history. Another sunny sign for consumers, diesel fuel, used by truckers transporting many goods, is averaging $2.67 a gallon in Massachusetts. The rise in that fuel earlier in the year led to sharp hikes in consumer goods - mostly food items.

While home heating oil has also dropped significantly, many homeowners who heat with oil locked into more costly contracts with oil providers in the summer and fall, when prices were high and expected to mount.