The following study was performed to investigate the in-use emissions performance of a California TLEV equipped with components aged in customer service on an enhanced I/M test. Fuels and ambient temperature conditions were chosen to compare I/M test conditions typical for California (moderate temperature on California Phase II gasoline) to those likely to be encountered in a Northeastern state (cold temperature on Winter grade fuel). To obtain repeatable results and simulate typical customer driving prior to the test, Bag II of the FTP schedule was used to simulate urban driving to an I/M lane, followed by a variable length idle to simulate waiting for the I/M test, followed by the IM240 test. For a given idle period prior to the test, we found that the IM240 tailpipe emissions were dramatically increased using cold conditions and federal winter regular unleaded grade fuels with higher sulfur levels as compared with similar tests in warm conditions using a California phase II reformulated fuel. The magnitudes of the emission increases measured for this particular vehicle are far greater than the average increases predicted by EPA models. Since the most strict emission standards for enhanced I/M can be based on these models, our results suggest that this vehicle would likely pass the most strict I/M TLEV cutpoints under conditions expected for California, but would surely fail the most strict I/M TLEV standards under conditions expected outside California.