Yes, we'll have to agree to disagree

.
I feel that the EPA is off the rails crazy and completely insane with regards to diesel emissions, more then likely because they 'look' bad, while the visual aspect is arguably less harmful than other aspects of diesel emissions... The soot is carbon, which will settle to the ground and return to nature. I've been behind equipped vehicles in regen (not to mention the first regen after the turbo failure in the Jetta) and the stink was eye burning AWFUL. I would rather smell exhaust from a diesel that has no CAT, or , as the ones that have those components stink so bad they burn my eyes (YMMV). I would not be the slightest bit shocked if they only took into account 'normal operating' emissions, and 'omitted' regen emissions, and if adding regen emissions into the equation would make overall emissions worse than non- vehicles, again, I would not be at all shocked. Also consider what I previously posted - they forced the on us claiming the soot was harmful. Ok, maybe it is to a degree... but on the other hand, there is no way on earth the can prevent ALL particulate matter from escaping, and that which is most likely to escape would be the smaller ash particles (Only a plug could prevent any and all matter from escaping, and we all know that won't work). These ash particles, obviously, are smaller than the soot particles, and thus are capable of 'burrowing' deeper in soft tissue (think asbestos)... I guarantee they can't (or won't) quantify how much ash can escape, but I also guarantee it's not zero. Not saying either is 'great', but one WILL degrade back into nature, the other won't, and one can get deeper into soft tissue than the other... Lets face it - the 2001 Duramax was orders of magnitude cleaner than the diesels of the 1980's, and I think that's a lot of where this crap comes from. That and the idiots that want to 'roll coal' - I'll admit, at one time, my truck smoked like a train if I got on it, not not because I wanted to, but because the tuning of the time sucked.... Now, with the tuning I have (which puts down more power than it did in the days it smoked like a train), in the last pulls I ran in, my truck put out no major smoke {maybe a slight haze at first, at most}, but overall, was FAR cleaner than almost any other truck, including those that didn't pull as far as me. I really only get any smoke whatsoever if I lug it... If the turbo is remotely spooled, forget smoke. These days, with the quality of tuning available, there is no reason for excessive smoke unless you're a retard that want's a 'smoke switch'. I love being able to put bus lengths on some smoking POS Cummins while not smoking at all. A good, clean running tune is the way to go.
I know they'll claim 'SMOG', however, I also know from things I've read in the past, that places most known for smog, such as Los Angeles, have historical reports of smog LOOONG before anyone (of todays magnitude) lived there, let alone the internal combustion engine even existing.
If they REALLY want to lower emissions overall, then they should 'mandate' biodiesel... overall, biodiesel has lower emissions than dino diesel - and it has the side effect of being RENEWABLE (Same goes for Ethanol, with a side effect of Ethanol being a great race fuel if tuned for it, as it has a very high octane rating)!!!! There is another fuel that is not 'technically' Biodiesel, but is renewable and overall seems to share similar traits, that escapes me... But as I eluded to previously, money talks... hence the oil companies squash renewable fuel options rather than embrace them as their future (Dino WILL run out - maybe not in the next 25, 50, 100, 200 years, but it will eventually... weaning off dino to bio is sound strategy ). Think of all the desert land that is useless for virtually anything - Algae based Biodiesel farms...
On the other hand, gas vehicles really haven't changed much, emissions wise, in the last 20+ years. My 21 year old Cougar has pretty much all the same emissions components as the latest gas vehicles. Probably the biggest difference is some/most newer vehicles have VVT, which, while not really an emissions component per se, allows the manufacturer to eliminate the system because they can use VVT to promote exhaust scavenging in place of . Beyond that, there is almost no difference.
Diesels, on the other hand, are another story. on a diesel is a HORRIBLE idea - you should have seen the buildup in the intake system on my 04 Duramax at 30k. There is zero chance it would have made it to 100k without restricting 100% (without serious cleaning), and considering the buildup, it's not unreasonable to think it could potentially have ingested a big chunk of gunk and cause bigger issues... At the end of the day, (potentially) reduces diesel engines longevity as it basically makes an air filter pointless - while soot is generated in the combustion chambers, introduces even more, pre combustion - soot isn't CO2, and while still a natural component, it's more abrasive than CO2, and the potential for wear is greater. EGRs negative effect in a gas vehicle is negligible. Diesel, not so much.
My truck would have certainly clogged the system 100% before 100k if not for a massive cleaning. My grandfathers 97 dodge/cummins plugged the cat to the point he couldn't get up any grade whatsoever while pulling a camper cross country. I'm sure neither of us are alone with these kinds of issues, and they simply don't happen with gas powered vehicles. The emissions components on diesels, on the whole, have a more detrimental effect than positive effect. The environmental impact is minimal (the VW 40x over violation amounts to GRAMS per vehicle, not TONNES), yet the impact to consumers is high. How many millions has TDI 'failures' (full, cracked, whatever - the dealer says replace) costed consumers?
In the end, the US is, more then likely, by far, the cleanest nation in the world, emissions wise, with China continuing to contribute more than the vast majority of problems to the atmosphere. Even still, the EPA is off the chain crazy. If they REALLY had their way, they would have some kind of device attached to every cows butt in the country (cat converter or some capture device), as cows emit probably at least as much methane into the environment as cars do CO2 and other elements)... They would require all power generated by solar, wind or hydro... NO coal, NG, etc... That's not going to happen any tie soon. I'm not really against being reasonably clean, but we can only reduce our emissions so much. China is not going to stop. They will only increase, and continue to be the major contributor to pollution. If you consider everything overall, keeping our emissions at 2001 levels while China coming to our 2001 levels would have a FAR greater impact than eliminating all emissions in the US, with everyone driving solar/wind/hydro/human power electric vehicles and NO internal combustion engines/fossil fuels/renewable fuels whatsoever. But good luck getting that to happen.
At the end of the day, they should provide a legal option to delete this crap. If they provided a legal option to delete it all to those 'performance minded' (or otherwise), I suspect that the impact would be near nil, because a VERY small overall minority would really fit into that category. The next would be those where the emission crap REALLY hurts them - like those that spend weeks in the middle of nowhere (drilling fields), idling, etc, EMERGENCY VEHICLES (a subject that is close to me being a former VF - I would be PISSED if I ever saw someone I worked next to stranded with their equipment because the emissions crap failed, not to mention the additional property or LIFE loss caused by said failure

). Again, a VERY small number. Barring those, most people (probably 98%+) don't care, as long as it works, which is where the last bit comes in - as I've said before, if they want this crap, then it should be warranty for the life of the vehicle (not original owner - the vehicle). The second half of that, however, is it needs to be reliable. The SINGLE.BIGGEST.COMPLAINT that I've heard about the newer trucks has been emissions systems. At this point, the DEF. A lifetime warranty on all components (we know how VW loves to try to say the filter is not an 'emissions component') except for sensors would be a good start, however, this crap stranding you in the middle of nowhere is hardly a good thing.... I don't believe for a second they can make this crap reliable enough for emergency vehicles. Hell, I remember an old firetruck my stepfather owned that had dual coils and dual spark plugs per cylinder (It may have also had dual distributors as well - this was long ago before I learned as much as I have about vehicles)- The coil was next to the only thing that could fail, meaning if a coil failed, the truck could move on. That's not possible with this emissions crap - if it fails, you're screwed.
I know we disagree on the emissions aspect of things, and I'd be happy to debate you in another thread or PMs if you wish, but I think we've gunked up this thread enough

. If we don't debate this elsewhere or chat again, I wish you the best in your endeavors. Hopefully I've contributed some small useful bit to this thread.