What loss did the owners actually suffer?
I presume MPG wasn’t affected so the running costs were no different.
The angst of unknowingly and unwittingly contributing harmful emissions to the atmosphere? Emissions linked to cardio-pulmonary disorders, asthma and other conditions? Of buying and driving a car that did not "do what it said on the tin"? Of choosing one particular model over another because of its supposed mix of performance, economy and cleanliness? The theoretical loss of having a car that nobody wants to buy second hand, thus having lower trade-in or resale value?
Most of the arguments I have seen are theoretical, however selling millions of units under
deliberately created false pretences must have consequences. I had one of the VW cheaty-diesels (in a Skoda). When I found out about what they had done (by the way, they were not the first to do this, nor allegedly the only ones) I immediately knew that any 'fix' would be detrimental to the car. They claimed they could fix the emissions with no loss in performance but knowing what I know I knew this was thermodynamically impossible - after all, if it were possible then it would have been how the car left the factory. I therefore refused the numerous attempts to 'fix' my engine and sure enough I saw increasing numbers of issues being reported on 'fixed' cars, the sorts of issues I predicted would happen: EGR issues, DPF regen issues, fuel economy issues etc.
In truth the cars will have run more economically on the cheating software but since it is impossible to calculate how much fuel you
did use vs how much you
would have used, and how much the car
is worth vs how much it
would have been, any loss (or not) is open to enormous interpretation and assumption. You can't escape the fact that the cars did not perform as specified and were technically illegal as they didn't meet (nor even get close to) European emissions legislation demands. This wasn't a case of ignoring unwanted data, it was a case of actively looking for, developing and implementing ways to cheat the testing protocols.