WESTLAKE VILLAGE, Calif. — Heavy truck customers are increasingly experiencing problems with heavy-duty truck engines that meet recent EPA-regulated emission standards, according to the J.D. Power and Associates 2006 Heavy-Duty Truck Engine/Transmission Study released yesterday.

The study, now in its 10th year, examines engines supplied in 2004 model-year trucks and measures customer satisfaction with the engines in two-year-old heavy-duty trucks (Class 8) by examining four vital engine factors: Engine quality; engine performance; engine cost of ownership; and engine warranty.

About 2,500 primary maintainers of two-year-old heavy-duty trucks were interviewed.

The average number of reported engine problems, according to the survey, has increased to 74 PP100 (engine problems per 100 vehicles) — up from 46 PP100 in 2005.

“In the 2005 study, there was a greater mix of manufacturers using old- and new-technology engines, so we’re just now starting to see the overall impact of the emission regulations,” said Brian Etchells, senior research manager in the commercial vehicle group at J.D. Power and Associates. “Whenever a new technology is employed, it takes a while to work the bugs out. As time goes on and engines are better equipped and designed to follow the emission standards, the number of problems should gradually decline.”

The study also finds that among the four drivers of engine satisfaction, customers are least satisfied with the cost of ownership, particularly in the areas of routine engine maintenance costs and fuel efficiency. Reported fuel consumption for heavy-duty engines has declined to 5.72 mpg in 2006 — down from 5.91 mpg in 2005 and 6.04 mpg in 2004.