The price of diesel fuel dropped 4.5 cents per gallon last week — to its lowest level in 15 weeks — and might have fallen even more if it were not for the high price of natural gas, a market analyst says.

Layoffs and job eliminations among major truck manufacturers topped 11,900 this year as companies cut back production to try to match costs with falling orders.

The Environmental Protection Agency’s proposed standards for heavy-duty diesel engine emissions in 2007 have produced an argument that has bounced back and forth for months among engine manufacturers, the makers of antipollution devices and oil refiners.

The price of diesel fuel dropped 2.3 cents last week following, but not keeping pace with, a steep slide that took the price of crude oil below $30 a barrel for the first time in four months.

Marc Gustafson believes it is time for some changes in the way truck manufacturers operate, and as chief executive officer of Volvo Trucks North America, he has begun to implement new practices at his own company.

Marc Gustafson believes it is time for some changes in the way truck manufacturers operate, and as chief executive officer of Volvo Trucks North America, he has begun to implement new practices at his own company to bring spec'ing to an end.

Dorsey Trailers, whose roots go back to 1911, has stopped making new trailers at all three of its manufacturing plants and is considering filing for bankruptcy protection.

The price of diesel fuel rose 1.8 cents last week, the third consecutive increase — and a trucking industry analyst said strong demand for distillates will force further increases regardless of the weather.

Caterpillar and DaimlerChrysler say their new alliance will produce joint sales in medium-duty engines and fuel systems of more than $3.8 billion by 2006.

Diesel fuel prices jumped 2.4 cents per gallon last week, reversing four weeks of decline.