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Emission Test Cycles

California Unified Cycle (UC)

Time-speed data points

The California Unified Cycle (UC) is a dynamometer driving schedule for light-duty vehicles developed by the California Air Resources Board. The test has been also referred to as the Unified Cycle Driving Schedule (UCDS) or as the LA92 (also spelled LA-92) cycle. The test is often called the “Unified LA92”, to distinguish it from a “short LA92”, which includes the first 969 seconds of the Unified LA92.

One of the applications of the UC cycle is testing of vehicles fitted with direct ozone reduction technologies (the Supplemental Federal Test Procedure, SFTP, was used for that purpose earlier).

The UC test, Figure 1, has a similar three-bag structure, but is a more aggressive driving cycle than the federal FTP-75; it has higher speed, higher acceleration, fewer stops per mile, and less idle time. The UC test is run in the following manner: Bags 1 and 2 are run consecutively, followed by a ten minute hot soak, then Bag 3 which is a duplicate of Bag 1. Overall cycle emissions are calculated in the same manner as the weighted, overall FTP-75 formula, taking actual mileage from the UC into account.


Figure 1. California Unified Cycle

The following are some characteristic parameters of the cycle:

  • Unified Cycle:
    • Duration: 1435 seconds
    • Total distance: 9.8 miles (15.7 km)
    • Average Speed: 24.6 mi/h (39.6 km/h)
  • Bag 1:
    • Duration: 300 seconds
    • Total distance: 1.2 miles (1.9 km)
  • Bag 2:
    • Duration: 1135 seconds
    • Total distance: 8.6 miles (13.8 km)