Following a request made by Japan’s Ministry of Land, Infrastructure, Transport and Tourism (MLIT), issued to Japanese automakers on July 9 2018 after the discovery of fraudulent testing practices at other companies, Mazda Motor Corporation submitted a report to MLIT on the results of an investigation into its sample testing of fuel economy and emissions during final vehicle inspections.

The investigation covered JC081 and WLTC2 testing modes and the key findings of the report are:

  1. No improper alteration or falsification of test data in either mode.
  2. Test data containing speed trace errors* was found in 72 cases out of 1,472 vehicles tested under the JC08 mode.  The company has identified two reasons for these errors. Firstly, the system was not set up to automatically invalidate results when a speed trace error occurred. Secondly, test procedures left the determination of speed trace errors up to each individual inspector.
  3. All test data has been re-examined and the results show there was no effect on specification fuel economy and emission figures. No such cases were found in WLTC mode testing.

Mazda has decided to take the following steps to prevent a reoccurrence:

  • The system will be updated to automatically treat test results as invalid in the event of a speed trace error.
  • Mazda has increased the number of employees who check inspection data, including speed trace errors.

Mazda accepts that errors were made on a small number of tests and the situation was identified quickly and steps have been put in place to avoid it happening in the future.

* A situation in which vehicle speed deviates more than the permitted amount from the speed trace pattern prescribed by the test mode

1 JCO8: Japanese 2005 emission regulation introduced a new JC08 chassis dynamometer test cycle for light vehicles (< 3500 kg GVW). The test represents driving in congested city traffic, including idling periods and frequently alternating acceleration and deceleration. Measurement is made twice, with a cold start and with a warm start. The test is used for emission measurement and fuel economy determination, for gasoline and diesel vehicles.

2 WLTC: The Worldwide harmonized Light vehicles Test Cycles (WLTC) are chassis dynamometer tests for the determination of emissions and fuel consumption from light-duty vehicles. The tests have been developed by the UN ECE GRPE (Working Party on Pollution and Energy) group. The WLTC cycles are part of the Worldwide harmonized Light vehicles Test Procedures (WLTP), published as UNECE Global technical regulation No 15 (GTR 15). While the acronyms WLTP and WLTC are sometimes used interchangeably, the WLTP procedures define a number of other procedures—in addition to the WLTC test cycles—that are needed to type approve a vehicle