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Trucks operating in inter-modal (drayage) operation in and around port and rail terminals, are responsible for a large proportion of the emissions of NOX, which are problematic for the air quality of the Houston and Dallas/Ft. Worth metro areas. A standard test cycle, called the Texas Dray Truck Cycle, was developed to represent the operation of heavy-duty diesel trucks in dray operations. The test cycle reflects the substantial time spent at idle (~45%) and the high intensity of the on-road portions. This test cycle was then used in the SAE J1321 test protocol to evaluate the effect on fuel consumption and NOX emissions of retrofitting dray trucks with light-weight, low-rolling resistance wide-single tires. In on-track testing, a reduction in fuel consumption of 8.7% was seen, and NOX emissions were reduced by 3.8% with the wide single tires compared to the conventional tires.

Fuel economy (FE) and greenhouse gas (GHG) emissions measured via chassis testing under laboratory conditions were never intended to represent the wide range of real-world driving conditions that are experienced during a vehicle's lifetime. Comprehensive real-world information is needed to better assess US FE label adjustments, determine off-cycle credits for FE standards, and forecast real-world driving behavior, fuel consumption, and CO2 emissions. This paper explores a cost effective method to collect in-use fuel consumption data using the on-board diagnostics (OBD) data stream in light-duty vehicles (LDVs). The accuracy of fuel consumption calculated from the OBD data was analyzed in two ways. First, fuel rates calculated from standard OBD Parameter IDs (PIDs) were compared with fuel rate estimates based on enhanced PID (OEM fuel injector fuel rate) data in two different vehicles.