^^ok, lol, not technical enough. I am not able to speak to the engineering specifics. There is a PowerPoint circulating that dates from when the gen 2 engine was released. It is a cleaner, more efficient diesel engine than what it replaced. Meanwhile, the emissions system was also reengineered around better recirculation of exhaust gases. The 2016 models use adblue at a much more normal rate than the earlier models, needing refills at around 7000 miles for the Touareg as opposed to the ridiculous, 15000 miles rate as older models. VW was already pulling the engines towards compliance, probably as they were already being investigated by the EPA.
This is why you see the 15’s and 16 Touareg and Cayenne models only needing a software replacement as opposed to a hardware/software replacement.
Also, I suspect that where one thinks one sees a compromise between opposing interests, there is actually mutual agreement. I suspect VW hoped that all the 3.0 engines would be blessed by the EPA, but as the negotiations moved towards a new administration taking over, both sides wanted an agreement in place to avoid uncertainty. The parties split the difference on agreeing that there would be a buyback on gen 1mand a fix on gen 2.
