[jyl]

There are two different issues here.

The first is that EPA testing procedures may not accurately duplicate normal (real world) on-road driving. This is also the case in the EU. The US and EU are going to improve procedures to be more realistic. All the car companies know that their cars pollute more in real world driving than in the test loop; the emissions controls, even though fully operational, don't work as well in the real world. This seems to apply to gas as well as diesel cars, from many carmakers. So, the regulators will have to decide how much slack to cut, and the carmakers will have to improve their controls, to meet somewhere in the middle.

The second is that VW diesels included software that is specifically designed to turn on full emissions controls during emissions testing, and turn off emissions controls during other driving. That is a deliberate evasion of pollution laws. As far as I know, VW is the only company that did that. If another company did it too, then that CEO had better be looking for his golden parachute. VW is throwing engineers under the bus as hard as it can, but that isn't enough.