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The Vehicle Exhaust Simulator is a tool developed to evaluate the performance of vehicle emissions sampling and analytical systems. Simulating a vehicle's emissions with accurate and repeatable equipment, rather than using a vehicle to produce emissions, eliminates several sources of variability (e.g. driver, dynamometer, vehicle) and isolates the performance of the sampling and analytical systems. Use of the Vehicle Exhaust Simulator includes: diagnosing test site problems, tracking performance over time, establishing correlation between emissions sites, and acceptance testing of new emissions sampling and analytical equipment. The Vehicle Exhaust Simulator was developed to emulate emissions from low-emitting gasoline vehicles. Federal Test Procedure (FTP) 3-phase bag values (THC, CO, CO2, and NOx) from an Ultra Low Emissions Vehicle (ULEV) have been used for most of the testing.

Numerical models for a variety of vehicle emission measurement systems have been developed using Mathematica® software. The sampling systems evaluated include the Constant Volume Sampler (CVS) and the Bag Mini-Diluter (BMD). The CVS system was evaluated as the conventional fixed flow rate system and in a number of configurations designed for improved performance. The enhanced CVS system employs flow rate switch between phases and heated dilution air. This system with various other enhancements was also evaluated. The additional enhancements included proportional ambient sampling, dilution air refinement, heating of system including bags, and heated system with dilution air refinement. Lastly, the Bag Mini-Diluter system was evaluated. The purpose of these models is to help determine which system will be the most effective strategy for Ford Motor Company to utilize for SULEV and below emission measurements.