ATLANTA The nation's largest operator of garbage trucks reports that its initial impression of the 2007 reduced-emissions diesel engines is positive.

In fact, the engines are performing much better than Waste Management executives expected.

John Lemmons, director of fleet and equipment performance at Waste Management, said in remarks at the Waste Expo trade show that data from the 10 '07 trucks the company currently has on the road shows nearly the same fuel economy as its 06 models.

Also, Waste Management has been able to extend its oil drain intervals to 600 hours with the CJ-4 oil required for '07 engines.

"These engines still need to be run in more to give us more accurate long-term data -- but we expected much, much worse preliminary performance data than what we are seeing," Lemmons told a trucking publication.

Since the "oldest" '07 vehicle Waste Management has in its fleet was only put into service in November, it's still relatively early to say whether the new engines will remain "fuel economy neutral" over the long term.

Another surprise and unexpected benefit from the 07 engines is that both horsepower and torque have increased compared with '06 models, with Waste Management's drivers reporting a noticeable improvement in the power and responsiveness of the trucks, he said. "That's another part we've been happy about."

Still, there is a downside to '07 technology, he cautioned. The new engines added $10,000 to the base sticker price of Waste Management's refuse trucks.

Meanwhile, from a performance perspective, Lemmons said the '07s are surprisingly good, and he hopes that doesn't change as testing continues. "We're pretty amazed that fuel economy remained flat between our '07 and '06 trucks running the same routes. That is pretty encouraging."