According to the J.D. Power and Associates’ 2009 Medium-Duty Truck Engine and Transmission Customer Satisfaction Study, fuel economy has improved considerably among 2007 model-year medium-duty engines, compared with 2006 model-year engines. The result, said the company, has been an increase in owner satisfaction with these engines.

The study, released yesterday, measures customer perceptions of 2007 model-year Class 5, 6 and 7 gasoline and diesel engines. Four factors are measured to determine overall engine satisfaction, said J.D. Power, noting they are in order of importance: engine warranty, engine quality, engine performance, and cost of engine ownership.

The 2009 study found that 2007 model-year medium-duty engines have considerably higher fuel economy than 2006 model-year engines did in the 2008 study. Fuel economy improved the most for Class 6 trucks, averaging 9.4 MPG-- compared with 8.8 MPG last year. Fuel economy gains were less notable for Class 5 and especially Class 7 trucks, the company noted. However, it stated that the average reported fuel economy improved from 2008 for five of the seven medium-duty engine manufacturers included in the study.

The improvement in fuel economy drives an increase in satisfaction with the cost of ownership factor, as well as an improvement in satisfaction with medium-duty engines overall, J.D. Power pointed out.

"With business owners trying to minimize expenses in this tight economy, reducing the cost of ownership--particularly their fuel expense-- is top of mind," said Brian Etchells, senior research manager in the commercial vehicle group at J.D. Power and Associates.

Hino Trucks engines ranked highest in customer satisfaction for the second consecutive year with a score of 776 on a 1,000-point scale. J.D> Power noted they performed particularly well in the engine quality and engine warranty categories. Mercedes-Benz (755) and Caterpillar (742) followed Hino in the rankings.

"Hino Trucks engines continue to perform well across the board, particularly with regard to quality," said Etchells. "When compared to the average engine in this market, Hino Trucks engines tend to have fewer engine problems and less downtime."

The 2009 Medium-Duty Truck Engine and Transmission Customer Satisfaction Study is based on responses from 1,589 primary maintainers of two-year-old conventional medium-duty trucks. The study was fielded in July and August 2009. For more information or to view medium-duty engine rankings, go to