How Volkswagen cheated on the auto emissions rules

From Hot Air:

This story is a bit far afield from the normal politics and crime beat, but given how it just came at us out of left field it’s worth questioning whether or not a much larger can of worms has been opened up. The EPA announced this week that Volkswagen was in a lot of trouble – potentially facing billions of dollars in fines – for allegedly rigging the system and creating diesel cars which were designed to cheat on emissions tests during inspection. And they don’t seem to be disputing it, either. (Yahoo Finance News)
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Exit question: how likely is it that the geniuses at VW and Audi were the only ones to dream this up? This sounds like the sort of thing that a group of engineers might assume was never going to be found out because who is going around doing extra testing of vehicle emissions outside of an inspection station? (In fact, I’m still wondering how the EPA caught on to this unless VW had a disgruntled whistle blower among their ranks.) Are the big, American automakers scrambling right now to cover their own code?

This could be quite a industry scandal, if it's widespread.

UPDATE: Instapundit has a thought!

And once again, as with their attacks on Toyota in 2010, note that the US government is gunning for a non-UAW approved automaker.

Coincidence?