The problems involve electronic controls and diesel particulate filters, which makes customers un happy.
Hino, Freightliner and Ford, meanwhile, scored well in Power's product index rankings for truck manufacturers.
While the quality of medium-duty trucks has improved considerably during the past five years, overall customer satisfaction has declined during the same period, according to the J.D. Power's 2011 U.S. Medium-Duty Truck Customer Satisfaction Study.
The study found that incidence of owner-reported problems decreased by 26% between 2007 and 2011, on average, an indication of higher quality. Yet during the same time frame, owner satisfaction declined by 27 index points (on a 1,000-point scale) among trucks that have been in service 13 to 18 months.
"On the surface, it seems contradictory that owner satisfaction would decline at the same time that owners reported fewer problems," said Brent Gruber, senior manager of commercial vehicle practice at J.D. Power. "Yet, when we dig deeper, we find that it's not the number of problems, but the nature of the problems that are causing owners to be less satisfied with their trucks."
The study finds that manufacturers have made dramatic improvements during the past five years in wheel/tire, braking system, and cab/body quality, resulting in a decline in the total number of problems. However, the number of engine problems in trucks that have been in service 13 to 18 months increased by 13 problems per 100 vehicles (PP100) between 2007 and 2011.
"Electronic control module calibration and regeneration system problems now impact 46% of medium-duty truck customers who experience an engine-related problem," said Gruber.
The study, now in its 19th year, measures customer perceptions of 2010 model-year Class 5, 6 and 7 commercial trucks. Within the product index, six factors are used to determine overall satisfaction: engine; warranty; cost of operation; cab and body; ride/handling/braking; and transmission.
The study also measures satisfaction with services received from an authorized truck dealer. Six factors comprise the service index: service facility; service quality; service advisor; service initiation; service delivery; and service price.
The study found that Class 5 trucks have the highest quality levels in 2011, averaging 76 PP100. In comparison, Class 6 trucks average 181 PP100, and Class 7 trucks average 144 PP100.
While medium-duty trucks are not typically considered to be environmentally friendly vehicles, the study found that some truck owners are thinking "green." Sixteen percent of owners say they are "certain" or "practically certain" that they would buy a truck from a green-rated manufacturer rather than a manufacturer without a green rating.
"Green ratings and technology are areas where manufacturers can differentiate themselves from the rest of the industry," Gruber said. "Manufacturers that invest in green technology and widely incorporate it in their trucks will have a considerable advantage in a very competitive market."
Hino ranks highest
With a score of 807, Hino ranks highest in customer satisfaction within the conventional truck segment for a second consecutive year. Hino performs well across all factors driving satisfaction, particularly in engine satisfaction and overall quality.
Freightliner (762) and Ford (757) follow in the product index rankings. Freightliner experiences the greatest improvement from 2010, increasing by 12 index points primarily due to higher engine and cost of ownership satisfaction.
The 2011 U.S. Medium-Duty Truck Customer Satisfaction Study is based on responses from 1,037 primary maintainers of 2010 model-year Class 5, 6 and 7 conventional cab medium-duty trucks. The study was fielded between June and July 2011.