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They've got EGR (which has been around forever), a reducing catalyst (not that much different than what's on all gas cars), and a DPF. The DPF is the only new thing, but from what I understand, it's a fairly simple piece. At least the VW diesels don't have a urea tank you have to refill every 15K!
At first glance, the only difference appears to be the DPF. Like you say, they've had EGR for a while now.
Thing is, it's not that they've had EGR, it's how much EGR they've had. In order to meet the NOX requirements for Tier 2 Bin 5, they use obscene amounts of EGR... like 30-40% compared to
If you want my opinion, I would prefer an SCR system and add the urea when needed, knowing that I'm not leaning so heavily on the EGR to do all the NOX control.
Of course, automakers didn't think American drivers will be willing to put up with the addition of yet another bit of maintaince in the form of urea. That's what the domestics thought with their trucks and look where it's gotten them. They not have a bunch of upset customers with broken EGR systems who are distrusting of clean diesel technology. The common "solution" to this is buying kits to eliminate the EGR valve.