When news broke that Mazda might have been caught cheating on emissions tests, the press moved quickly to report it. I didn’t, because I didn’t believe Mazda had it in them. Today, Mazda released more details about the “suspect” tests and their testing methods that seems to effectively refute those cheating allegations recently leveled at Mazda (and, it should be said, Suzuki).

The official Mazda statement is included, below. Before you read that, however, consider the culture of Mazda. Mazda is the company that drilled holes into seats, pedals, and bulkheads to reduce weight in the 90s. They’re the company that brought back the roadster. They’re also the company that forged ahead with the Wankel, and made it a workable, emissions friendly passing thing. Cheating at emissions tests isn’t like them, in other words. Unlike VW’s ex-Chariman Piech and his motorsports-groomed engineering teams at VW and Audi, Mazda wouldn’t pat itself on the back for finding a new loophole in the rules. Instead, they’d just quietly continue to build its cars, within the rules, and try to find success where others couldn’t.

Corporate culture is a real thing, in other words. It’s part of why you should love Volvo, clap when Mazda stands up for itself, and remind yourself, often, that VW was started by Nazis. And, if you think that’s a crazy thing to say, consider that VW planned to force human beings to breathe diesel emissions to see what would happen … recently.

Anyway, my opinion is that Mazda and VW are motivated by different things. That’s why I feel pretty safe coming out and saying that Mazda isn’t cheating emissions tests. Read the release, below, and let us know what you think in the comments section at the bottom of the page.


Report on fuel economy and emission testing confirms no improper alteration or falsification of test data by Mazda

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.



Source | Images: Mazda, via Motor 1.