Vocational truck owner satisfaction with their heavy-duty engines has improved notably from 2008, according to the J.D. Power and Associates 2009 Heavy-Duty Truck Engine and Transmission Study released Sept. 21.

Satisfaction with heavy-duty engines improves to 733 on a 1,000-point scale, up from 725 in 2008. Satisfaction scores for quality, performance and cost of ownership all increase markedly, compared with 2008. The percentage of customers with heavy-duty engines reporting an engine problem drops to 40 percent-its lowest point since 2005. In addition, the proportion of customers experiencing engine-related downtime also drops to the lowest level since 2005.

"The decline in engine-related problems is a testament to the engine manufacturer's focus on quality, particularly when you consider the environment in which these engines were produced," said Brian Etchells, senior research manager at J.D. Power and Associates. "During the 2007 model year, sales volumes increased to near-record levels as customers sought to purchase trucks prior to the introduction of emission reduction technologies on 2008 model-year trucks. Plants were adding shifts and struggling to fill orders, but despite these challenges, quality actually improved."

Now in its 13th year, the study measures customer satisfaction with engines in two-year-old heavy-duty (Class 8) trucks by examining four engine factors. In order of importance, they are: engine quality (30 percent); engine performance (26 percent); engine cost of ownership (22 percent); and engine warranty (22 percent).

Mercedes-Benz ranks highest in customer satisfaction with vocational trucks with heavy-duty engines for a second consecutive year, achieving an index score of 765. The manufacturer performs particularly well in the engine quality, engine cost of ownership and engine warranty factors. Cummins (748) and Caterpillar (747) engines, respectively, follow Mercedes-Benz in the rankings.

The 2009 Heavy-Duty Truck Engine and Transmission Study is based on the responses of 2,421 primary maintainers of two-year-old heavy-duty (Class 8) trucks. The study was fielded between February and April 2009.