ANN ARBOR, Mich. -- After badgering American manufacturers to produce cleaner, more-fuel-efficient vehicles, the Environmental Protection Agency is about to see its first product hit the streets. The engineers at the EPA's National Vehicle and Fuel Emissions Laboratory here have built and tested many prototypes over the years, including a diesel-hydraulic passenger car that gets more than 80 miles per gallon. But the first EPA-influenced product to travel beyond the laboratory will be a garbage truck. The garbage truck -- slated for rollout next year -- is a hybrid vehicle. Most hybrids use two power sources. In this case, the...