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> So the fuel consumption has not changed from before update for normal driving. So you won't see any difference.

Uh, I think you've got it backwards. Won't the updates mean it drives in 'test mode' (e.g. acceptable emissions that meet the standards) all the time? Meaning that it will result in some downside (which was apparently bad enough that they cheated in the first place)

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Specifically, reducing NOx (without using DEF) pretty much requires the engine to burn a richer mixture. This means more fuel injected, so less fuel efficiency and more unburnt hydrocarbons clogging up the particulate filter. Without retrofitting DEF systems onto the older cars, any fix is likely to be a significant hit to efficiency and reliability. I think maybe performance would suffer too but I forget how that would work.

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