Everyone knows about the drawing and quartering of VW over the "cheat" software embedded in the inscrutable labyrinth of code, deep within the "affected" cars' computers. The code tweaked the engines to pass the EPA's certification tests – passage of which serves as a kind of permission slip to sell cars – by making them produce hair-splitting differences less oxides of nitrogen (NOx) while being tested, to get them through increasingly unreasonable regulatory rigmarole designed to prevent them from being sold. Because diesels – efficient, practical and inexpensive – pose a threat to the expensive, inefficient and impractical electric car agenda, which is really an anti-driving agenda.

But that's another rant.

Out in the real world, unplugged from the government's testing rigs, the "cheating" cars produced fractionally more NOx, in the interests of better mileage and drivability.

This "cheating" being harmless; the same thing as using a radar detector to avoid being pinched by a cop for doing 45 in a 40.

 A rule (and the authority of rule-issuers) is affronted, that's all.

Another rule affronted applies to heavy trucks, which are almost universally powered by diesel engines (unlike most passenger cars, which are mostly powered by gas engines).

The rule – a regulation, to be precise –  was passed during the Bush decidership, when it was decided – arbitrarily, by government bureaucrats in the EPA – that heavy truck diesels built after 2004 would be subject to a ratcheting up of whatever the prior arbitrary standard was.

But the new arbitrary standard, though arbitrarily higher, was objectively too expensive to comply with. It cost too much to make heavy-truck diesel engines "complaint," in the patois of the bureaucracy – and these engines weren't as fuel-efficient and cost more to operate than the older, "non-compliant" ones.

It is the reason why Caterpillar went John Galt, shrugged – and stopped making diesel engines for on-road use entirely. But Caterpillar could survive by making diesels for off-road heavy equipment.

Others can't.