In Volkswagen's Defense
First, let me say that I drive a Volvo XC70 - a 300 HP, 5000 pound, gas guzzler that gets about 9,000 miles per ticket -- and have never owned, or wanted, either a Volkswagen or an Audi.
It's unfair to hold today's Volkswagen AG accountable for the sins of its founders, but I have never understood how leftist anti-war protestors and peaceniks could commute to their riots in cars and vans whose design Ferdinand Porsche largely stole from Tatra at Hitler's orders -- but then, I don't understand how adoring posters of mass murderers like Mao and Che Guevara with peace symbols and flowers makes sense either.
The bottom line on both observations, however, is that I don't like VW's cars, don't like the company, and have no friends who bought that company's products new - but none of this means that I can't see the upside of what VW is said to have done.
Specifically, it is possible to see their "defeat device" (basically a piece of software that detunes diesel engines during testing, but lets them run hot and clean in actual customer use) as an inspired bit of civil disobedience.
So, with that in mind, here's how Volkswagen could use the difference between the "de facto" real world application of the rule and the "de jure" world of law to defend themselves.
The legal defense is straightforward: the law generally requires these engines to pass EPA specified tests at the time of testing -- and they do. This is, in most jurisdictions, simple, black letter law: there is literally no legal substance to the charge against them.
The reality based defense, however, would be that the rule is known to be both unrealistic in economic and technical terms, and environmentally counterproductive. Basically VW would defend itself by attacking the rule maker and pushing the idea that the whole is thing is driven by the leftist agenda, not environmental concern.
There are two reasons this works:
1. The costs of the rule are easy to quantify, but the deaths due to NOx and particulate matter cited to justify it exist only as a computational artifact -- in reality not a single death, or even major illness, can be directly attributed to NOx or particulates emitted from a VW, or any other diesel, in normal outdoor use.
Some useful measures of the environmental impact that would have been produced had the rule been followed are, furthermore, both easy to estimate and easy to defend as real.
To illustrate I'll make up some ballpark numbers: suppose the net effect of the rule if applied would be to decrease the mileage your (lying) neighbor gets on his diesel Volkswagen from a claimed 68.75 MPG to a real 55 MPG -- in part because the engine burns fuel less efficiently and in in part because it has to run at a higher RPM to produce comparable power. Now assume 400,000 VW diesels averaging 20,000 miles a year over eight years, and you get the guess that the EPA wanted to force VW customers to buy and burn an additional 230 million gallons of fuel over the period. Figure an average $3 and 23 pounds of exhaust per gallon, and this rule shows as a $698 million dollar differential tax burden on VW owners -- and 5.3 billion pound assault on the environment.
2. This issue has a long history at both the EPA and VW with both sides well aware of each other's positions and actions since at least 1998. As a result VW can present the current blow-up as a politically motivated EPA action breaking a longstanding unspoken agreement to ignore a stupid rule known to be both environmentally and economically counterproductive.
Notice, in this context, that this type of rule doesn't originate with the Republican initiated and passed Clean Air Act, it originates with Carter's EPA; the key precedents were established (largely through real and threatened judicial activism) during the Clinton administration; and that VW's use of today's "defeat device" was enabled by Clinton-era requirements with respect to on-board automotive diagnostics and triggered by the fleet fuel efficiency requirements imposed by the Obamacon in 2009.
So, what's Volkswagen's defense? It met the letter of a law imposed by bureaucrats acting in bad faith on bad science; put its customers first; reduced environmental risks and/or exposure for all Americans; and is now taking that act of civil disobedience into the legal and political arenas in support of its customers, its shareholders, and the environment.
I don't thinking shouting "Sieg Heil VW!" wholly appropriate, but if they fight, no jury containing at least one articulate conservative is going to convict them -- and smarter customers will probably express their approval of the company's actions where it counts: at the dealerships.