
Emission control systems in modern cars have slashed air pollutants such as particulate matter and nitrogen oxides.
But these systems face two major challenges: carmakers cheating on pollution tests and owner tampering. Cheating means high-polluting cars can be sold when they shouldn’t be, while tampering can increase some pollutants by up to 100 times.
In our new research review, we found the impacts of cheating and tampering on emissions of pollutants are substantial across the globe. For instance, researchers in Spain found almost half the diesel trucks had been tampered with, while the Volkswagen Dieselgate cheating scandal uncovered in 2015 led to an estimated A$60 billion in health costs in the European Union.
In California, researchers found one in 12 trucks had a damaged or malfunctioning diesel particulate filter—and these high-emitting trucks contributed 70% of the entire fleet’s emissions of tiny particulate matter.
The solutions? Better detection of tampering, cheating and malfunctioning emission systems—and vigilance to get high-polluting cars off the road.
How did we get here?
From the 1950s onwards, smog, air pollution and health issues from car exhausts led many regulators to require carmakers to reduce dangerous air pollutants.
These days, modern combustion-engine cars are complex computer-controlled systems optimized to balance engine performance, durability and emission control. When working properly, new vehicles can reduce air pollutant emissions by 90% or more. However, they can increase carbon dioxide emissions by using slightly more fuel.
But these pollutants can soar if emissions control systems malfunction—or suffer from intentional cheating or tampering.
Cheating and tampering are not new. Cheating was first reported in the 1970s and it’s still happening. Tampering, too, dates back to the 1970s.
Both issues worsen air quality. These excess air pollutants have substantial costs to human health, as they can trigger respiratory conditions and can cause disability and premature death.
While the numbers of electric vehicles are rising, they’re only about 5% of the global fleet—about 60 million compared to about 1.5 billion cars powered by petrol, diesel and gas.
Because cars have relatively long lifespans, many fossil-fuel powered cars will still be in use in 2050, now just 25 years away. Many will be exported from rich countries to developing economies. That means effective pollutant control still matters.
Cheating by manufacturers
It’s well-established combustion engine cars produce substantially more emissions and pollutants during real-world driving than they do in regulatory tests.
There are many reasons for this, including natural wear and tear. But one big reason may be cheating.
Authorities in many nations rely on testing to see if a new model is emitting at rates low enough to meet emission standards.
Manufacturers can take advantage of the known quirks of official tests and intentionally alter how their vehicles operate during testing. To do this, they may install a “defeat device“, usually deep in the car’s engine or its computer code.
These devices shift the car to a special low-emissions mode if testing is detected. They’re typically easy for the automaker to install and difficult to detect.
Defeat devices are mainly found in diesel cars and trucks, since diesel emissions control systems are more complicated and expensive than petrol or LPG. Adding an emission control system to meet Euro 6 standards costs about $600 for a petrol car. For diesel, the cost can be three to five times higher.
In 2015, the United States Environmental Protection Agency and the state of California announced that Volkswagen had been using a software-based defeat device to make its diesel cars appear substantially cleaner. The scandal drew worldwide attention and cost the company about $50 billion.
For those caught, large fines and mandatory recalls have followed. But this hasn’t been enough to stop the practice.
The way these tests are conducted usually has to be disclosed by law to ensure transparency and make results comparable and repeatable. Unfortunately, having detailed knowledge of the tests makes it easier to cheat.
Tampering by car owners
Tampering is largely done by owners of diesel cars and trucks. Owners can tamper with emission control systems to improve performance, rebel against laws they don’t agree with or avoid extra costs, such as Adblue, a liquid needed to reduce nitrogen oxides emissions from diesel trucks.
Tampering is usually illegal. But that hasn’t stopped the production of aftermarket tampering devices, such as software which deactivates emission control systems. It’s not necessarily illegal to sell these devices, but it is illegal to install and use them.
In the road freight sector, the use of aftermarket tampering by vehicle owners also acts as an unfair economic advantage by undercutting responsible and law-abiding operators.
What should be done?
Combustion engine cars and trucks will be on the world’s roads for decades to come.
Ensuring they run as cleanly as possible over their lifetime will require independent and in-service emissions testing. Authorities will also need to focus on enforcement.
Creating an internationally agreed test protocol for the detection of defeat devices will also be necessary.
Combating tampering by owners as well as malfunctioning emissions systems will require better detection efforts, either through on-road emissions testing or during a car service.
One approach would be to add telemetry to the onboard diagnostics systems now common in modern cars. Telemetry radio transponders can report emissions problems to the owner and relevant authorities, who can then act.
Shifting to EVs offers the most robust and cost-effective way to combat fraud and cut exhaust pollutants and carbon emissions from road transport. But this will take decades. Authorities need to ensure diesel and petrol vehicles run as cleanly as possible until they can be retired.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Cheating by car makers, tampering by owners: Crucial car pollution control is being sabotaged (2025, June 12)
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