EPA Test Data Provides Fodder For Sparring Over Heavy-Duty Truck Rule

A new EPA memo detailing results from a heavy-duty diesel engine test shows a significant compliance margin with the agency’s stringent top-line proposed nitrogen oxides (NOx) standard for model year (MY) 2027 but some difficulty in meeting a key standard for MY31, findings that are spurring further sparring over the agency’s proposed rule. According to an industry source, the narrow MY31 compliance margin is likely to serve as fodder for truck makers to argue that EPA’s proposal is too stringent...