The transportation sector's CO2 reduction targets require significant changes to the vehicle fleet. Testing new vehicle technologies and fuels is essential to reduce carbon emissions without increasing toxic pollutants. This paper presents a case study on assessing fleet tailpipe emissions, useful for evaluating new vehicle technologies and fuels. The EU annual periodic technical inspection (PTI) provides a good opportunity to gather useful data, and can be enhanced with additional tests. Vehicle and tailpipe emissions data was collected using the parSYNC® iPEMS on over 600 randomly selected light duty vehicles conducting an enhanced PTI emissions test. The test utilised the idle, high idle and free acceleration portions of their EU PTI, as well as an additional short drive section incorporated into their PTI. The parSYNC® is validated against certification equipment. Many fleet characteristics were studied. For example, CO2 emissions decreased from Euro 4 to Euro 5 but plateaued to Euro 6. Petrol particle number (PN) emissions seem to require more control, while newer diesels have better PN management. Euro 6 diesel NOx emissions reversed the Euro 5 increase, though SCR deterioration was observed. The correlation between vehicle test and type-approval results was also examined. This study highlights the potential of enhanced PTI testing to assess the large-scale impacts of new vehicle technologies and fuels, ensuring their effectiveness and preventing pollutant backsliding.