Mitsubishi Faces EPA Scrutiny Over Decades-Long Fuel Economy Irregularities
The Growing Scandal: What We Know So Far
Mitsubishi Motors finds itself at the center of a mounting controversy as both the U.S. Environmental Protection Agency (EPA) and National Highway Traffic Safety Administration (NHTSA) investigate potential fuel economy irregularities in the automaker's vehicles. The probe comes after Mitsubishi's shocking admission that intentional falsification of fuel-efficiency data may extend as far back as 1991—spanning nearly three decades of production.
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Key Developments:
- EPA has requested new "coast-down" tests for U.S. market vehicles
- NHTSA confirms it's seeking information from Mitsubishi
- 625,000 mini-cars affected globally (primarily Japanese domestic models)
- No U.S. models currently confirmed as affected
Understanding the Technical Violations
The heart of the investigation revolves around "coast-down" testing procedures—a critical method for determining a vehicle's aerodynamic drag and rolling resistance. These factors directly impact official fuel economy ratings:
How Coast-Down Testing Works
- Vehicle is accelerated to high speed (typically 80+ mph)
- Transmission shifted to neutral
- Engineers measure deceleration rate
- Data calculates resistance affecting fuel efficiency
The EPA began auditing these tests in 2011 following Hyundai-Kia's high-profile mileage scandal where faulty testing led to overstated MPG figures. Industry experts suggest Mitsubishi's case could prove more serious due to the potential longevity of the irregularities.
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Global Impact vs. U.S. Market Implications
While 625,000 vehicles are affected worldwide—primarily kei cars (Japan's mini-vehicles category)—the investigation's focus on U.S. models raises important questions for American consumers:
| Market | Affected Models | Investigation Status |
|---|---|---|
| Japan | eK Wagon, eK Space, Dayz, Dayz Roox | Confirmed irregularities |
| United States | Under investigation (none confirmed) | EPA/NHTSA review ongoing |
Mitsubishi has established an independent investigation committee to determine if overseas models used improper testing methods. The automaker maintains that it's unaware of any affected U.S. models at this time.
Regulatory Response and Potential Consequences
The dual investigations by EPA and NHTSA represent significant regulatory pressure on Mitsubishi:
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EPA's Possible Actions
- Mandate corrected fuel economy labels for affected vehicles
- Require Mitsubishi to compensate owners for fuel cost differences
- Impose civil penalties (up to $44,539 per violation under Clean Air Act)
NHTSA's Potential Measures
- Order recalls if safety standards were compromised
- Require revised window stickers
- Mandate consumer notification campaigns
Legal experts suggest Mitsubishi could face class-action lawsuits similar to the $395 million settlement paid by Hyundai-Kia in 2014.
Consumer Guidance: What Owners Should Know
While the situation develops, Mitsubishi owners and prospective buyers should consider these steps:
Action Items for Consumers
- Monitor official communications - Check Mitsubishi's website and NHTSA recalls page
- Track real-world fuel economy - Compare actual MPG to advertised figures
- Document fuel purchases - Keep records in case compensation programs emerge
- Consult dealerships - Ask about any pending software updates or modifications
Industry analysts recommend against panic, as even if U.S. models are affected, the practical impact on most drivers would likely be modest—perhaps 1-3 MPG variance from advertised figures.
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Historical Context: Automotive Mileage Scandals
This investigation places Mitsubishi in unfortunate company with other automakers who faced similar controversies:
Notable Automotive Fuel Economy Scandals
- Hyundai-Kia (2012) - $395M settlement for overstating MPG on 1.2M vehicles
- Volkswagen Dieselgate (2015) - $30B in penalties for emissions cheating
- Ford (2014) - Revised ratings for 6 models after C-Max hybrid discrepancy
- Honda (2014) - Voluntary MPG restatements for Fit subcompact
What makes Mitsubishi's case unique is the potential duration of the irregularities—raising questions about quality control processes spanning multiple vehicle generations.
Looking Ahead: Next Steps in the Investigation
As regulatory scrutiny intensifies, several key developments are expected in coming months:
Short-Term Timeline
- Completion of independent committee's investigation (estimated 3-6 months)
- EPA review of new coast-down test results
- Potential expansion of probe to additional markets
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Long-Term Implications
- Possible restructuring of Mitsubishi's testing protocols
- Increased regulatory oversight of Japanese automakers
- Potential impact on Mitsubishi's partnership with Nissan
MotorVero will continue monitoring this developing story and provide updates as new information becomes available from regulatory agencies or Mitsubishi Motors.
