There is a long and sordid history of car companies using "defeat devices" to skirt government pollution and other mandated regulations mainly because the incentives to do so are significant. The first of these devices turned off the newly mandated emission systems when people used the air conditioning. Another device was a sensor that activated pollution controls only at the temperature regulators used during the tests.
Recent devices sensed when government devices were attached and calibrated the engine to perform in a manner consistent with what the government considered acceptable results. The car manufacturers are incented to do this because of the need to meet the challenging regulations set forth by governments world-wide with regard to things like emissions and fuel efficiency. These are difficult problems to solve and one way to solve it is to give the government what it wants, just not in the way it wants it.
VW and Fiat Chrysler are just the latest to come up with ways to manage the demanding and at times, conflicting government regulations imposed on them by countries. The VW situation is more rare with an admission of guilt and charges being brought against VW employees. The Fiat Chrysler situation is going to be more of what is seen in the future with the government claiming a company is cheating, the company saying it is complying and the devil is in the software details.
Your car is a robot. This gives manufacturers a lot of flexibility when implementing new features that humans demand and also managing government regulations. Your car/robot can execute actions just like a human does when driving though it comes at the expense of having to use a huge amount of software. Humans driving a car and driverless cars execute individual decisions thousands of times every second. We use our brains and the car uses software.
The bad side is that the software in the car that makes these decisions allows companies to implement an approach to managing government-mandated regulations in ways we might call unethical and illegal. Code to implement the equivalent of defeat devices are easily programmed in and when detected can be characterized as a "software defect" that can be fixed with a software upgrade to the car.
Sometimes the regulations and their nomenclature is imprecise so determining if the software is helping a car meet or defeat a regulation can be problematic. So far, manufacturers have paid fines and done recalls to the dealer so that the software can be updated. Maybe the car owner will purchase an oil change or new tires while they are there. Everyone wins?
Car software is proprietary meaning that no one can view the source code and analyze it for defects and there is no oversight to ensure the right decisions are made when creating the software and updating it. There is also a long and sordid history of companies resisting this level of public transparency. And the dynamic seen with VW and now with Fiat Chrysler is not just a "car" thing. This same issue is present in any complex software system such as medical devices, electronic health records, electronic voting machines, and other automated systems that now do what humans did.
The ugly side of our insatiable desire for better and better technology will see more Fiat Chrysler events until the technology providers are incented not to create better defeat devices. And more government regulations are not the solution – they just incent the creation of better defeat devices.
A good start? Make the car software open to the public. It is called transparency.