What are emissions test drive cycles and why are different cycles used?

Emissions test cycles are standardized driving patterns used to measure vehicle emissions and fuel economy under repeatable conditions. Different regions use different cycles: FTP-75 and US06 in USA, WLTP globally, NEDC (legacy Europe), and JC08 in Japan. Cycles differ in duration, speeds, and aggressiveness to represent regional driving patterns. Vehicles must be certified on applicable cycles for market access. The shift from NEDC to WLTP reflects demand for more realistic driving representation.