Source: J.D. Power
European diesel truck and engine brands placed highest in recent J.D. Power studies.

The biggest diesel trucks on the road have taken a "precipitous drop" in reliability as vehicle manufacturers have incorporated new emissions controls required by the U.S. Environmental Protection Agency, says one expert at J.D. Power and Associates.

In two separate studies this summer, J.D. Power surveyed fleet managers in the heavy-freight and vocational, or work truck, vehicle categories. The studies cover Class 8 trucks and engines for the 2011 model year, which was the first full year that the latest round of clean diesels were shipped to customers.

Engine and fuel-related breakdowns rose to 81 problems per 100 vehicles from 71 problems per 100 vehicles. The most common problems were failures of electronic control modules, exhaust-gas recirculation valves and electronic engine sensors, all of which work together to scrub emissions from a heavy-duty diesel engine. J.D. Power, like ENR, is a unit of the McGraw-Hill Cos.

Domestic Brands Suffer

The results were not surprising. "We expected to see some quality issues with the new engines," says Brent Gruber, J.D. Power director of commercial vehicles. He describes the latest results as a "precipitous drop" in quality from previous generations. However, suppliers appear to be responding faster than in the past. "What we've seen is that the cycle may be getting shorter and shorter," Gruber says.

One reason for the quicker turnaround may have to do with manufacturers shifting their vehicle platforms to a more global standard. European countries required the same emission controls approximately two years ahead of the U.S. 2010 deadline, so truck and engine makers operating in the eurozone are ahead of the learning curve compared to their U.S. counterparts. "They essentially had an opportunity to test them and work a lot of those bugs out," says Gruber.

This has put North American manufacturers at a noticeable disadvantage, J.D. Power says. This summer, Freightliner ranked highest in customer satisfaction for Class 8 trucks, while Detroit Diesel scored the highest points for heavy-duty diesel engines. Both companies are units of Germany-based Daimler.

Meanwhile, Navistar, a U.S.-based manufacturer, scored the lowest in the freight truck and engine categories, with below-average satisfaction for long-haul trucks. For vocational trucks, Freightliner again ranked first. Mack ranked lowest, just behind Kenworth, though Kenworth took the highest rating for dealer service.

"We saw a pretty big difference between those who were more global than those who were domestic," Gruber says.

Fading satisfaction has led some to think outside the box. For freight haulers, few options exist outside of diesel power. However, many users in the construction industry don't require the same type of duty cycles on the engines, which opens up the door for them to use smaller powerplants and alternative fuels (see this week's Equipment Tracks & Trends).