WESTLAKE VILLAGE, Calif. — The fuel economy of 2007 medium-duty truck engines has driven up owner satisfaction compared with that of the 2006 model-year, according to the J.D. Power and Associates 2009 Medium-Duty Truck Engine and Transmission Customer Satisfaction Study.

According to the study, 2007 model-year engines on medium-duty trucks has higher fuel economy than the 2006 models, with class 6 trucks averaging 9.4 miles per gallon, versus 8.8 miles per gallon last year. While class 5 and 7 saw less fuel economy gains, on average, fuel economy was improved by five of the seven medium-duty engine manufacturers from 2008.

The fuel economy factor made these engines more appealing to customers because of the cost of ownership, J.D. Power said.

"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.

The study 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. In order of importance, they are: engine warranty; engine quality; engine performance; and cost of engine ownership.

Hino Trucks engines ranked the highest in customer satisfaction for the second year in a row.