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Exhaust emissions of nitrogen oxide (NOx), total hydrocarbons (THC) and carbon mono-oxide (CO) in terms of sulfur concentration were mainly investigated according to the Japanese 10.15 mode driving schedule. Tested vehicles had direct injection engines with nitrogen oxide (NOx) selective reduction catalyst or NOx storage reduction catalyst as well as stoichiometric combustion engines with three-way catalyst. Direct continuous measurement of NOx, THC and CO was also conducted. Exhaust Emissions were measured using He injection and mass spectrometry. The air fuel ratio (AFR) and driving conditions that would promote sulfur removal were found to be important factors in reducing NOx further, for recent gasoline-fueled vehicles with emerging technologies using low sulfur fuels under 100 ppm.